Diagnosing and Troubleshooting

10:41:00 PM |


Certification Objectives

Common Error Codes, Startup Messages, and Icons from the Boot Sequence for DOS, Windows 3.x, and Windows 95
Correcting a Startup or Boot Problem
Creating an Emergency Boot Disk with Utilities Installed
Recognizing Windows-Specific Printing Problems
Common Problems and Causes
DOS- and Windows-Based Utilities and Commands/Switches
Installing and Configuring DOS Applications, and Potential Problems in Windows 95
Viruses and Virus Types
DOS, Windows 3.x, and Windows 95 all provide some error messages that can be used to help diagnose common problems, which can be resolved by some common solutions. Whenever you are installing or configuring any type of application, some errors can occur. In this chapter, we discuss some of these common problems and their solutions in addition to some of the tools that can be used to diagnose/fix these problems.

Common Error Codes, Startup Messages, and Icons from the Boot Sequence for DOS, Windows 3.x, and Windows 95

All operating systems that have ever been produced have provided some type of error codes to alert the operator to troubles. Unfortunately, many of these error codes are a bit difficult to understand. As we progress into the future, these error codes and startup messages have and will continue to become less incomprehensible. In this section, we discuss some of the common error codes and startup messages, and what they really mean.

DOS

DOS provides three major error messages that are dealt with in this section. These include:
Incorrect DOS version
Error in CONFIG.SYS line XX
Bad or missing COMMAND.COM

Incorrect DOS version

Whenever a utility is used, it makes some assumptions as to its abilities based on the version of DOS that it is being run on. When the utility first starts, it verifies that it is being run on the version of DOS it was designed for. If the version of DOS is not the version it was created for, the message "Incorrect DOS version" is displayed.
This problem should be fixed by using applications that were created for the version of DOS that you are using. As a workaround, the SETVER utility can be used to make applications think that they are running on the version of DOS that they want to be running on. To use SETVER, follow the instructions provided when you type "SETVER /?".

Error in CONFIG.SYS line XX

The message "Error in CONFIG.SYS line XX" (where XX is a number) tells us that there was an error in the CONFIG .SYS file when it was processed. The error can be found by counting the number of lines that are in the CONFIG.SYS file, and finding line number XX. You can then either fix the error by following the instructions that the manufacturer of the driver referenced by that line provides, or by simply deleting the line. The most common cause of this error is a missing file. After determining which driver is creating the error, you should verify that the driver still exists.

Bad or missing COMMAND.COM

Bad or missing COMMAND.COM most commonly occurs when the COMSPEC parameter is set in CONFIG.SYS, and the COMMAND.COM that COMSPEC references does not exist. This error can also occur when starting Windows 95.

Windows 3.x

Windows 3.x is a bit more advanced than DOS, so there are more advanced error messages that can be displayed from Windows 3.x. Most of the errors in the following list occur after Windows 3.x has begun to load, but the graphical user interface (GUI) is not displayed. The common error messages discussed here are:
HIMEM.SYS not loaded
Unable to Initialize Display Adapter
Swapfile Corrupt
A device referenced in the WIN.INI could not be found

HIMEM.SYS Not Loaded

Windows 3.x requires that the HIMEM.SYS driver be loaded in order to access High Memory. Windows 3.x needs to access memory above 640K, and uses the HIMEM.SYS driver to do so. This driver should be the first line in the CONFIG.SYS file. If in Windows you receive the missing HIMEM.SYS error, first verify that the first line of CONFIG.SYS is "DEVICE=C:\WINDOWS\HIMEM.SYS". If the line is in CONFIG.SYS, you should verify that HIMEM.SYS is in the specified location.

Unable to Initialize Display Adapter

Unlike DOS, Windows 3.x requires that you identify the video adapter that is installed in your system. If Windows gives you a "Unable to initialize display adapter" error, you should use the Windows setup utility to change the adapter type. If you are unsure of the exact model of adapter you have, VGA should always work, although it does not produce the best results. It is important to note that this error could also be the result of a faulty display adapter, but is less likely.

Swapfile Corrupt

Windows 3.x uses a swapfile in order to create virtual memory. In the event that this file becomes corrupted, Windows operates extremely slowly and gives you the message that the swapfile is corrupt. To remedy this problem, open the Control Panel, and go to 386 Enhanced. Change the swapfile setting to none, save, and reboot the machine. After the machine restarts, Windows will be extremely slow. Open the Control Panel again, go to 386 Enhanced, and return the swapfile settings to what they were before.

A Device Referenced in WIN.INI Could Not Be Found

In the event that a device that is referenced from the WIN.INI file cannot be found, you will receive this error. To eliminate this error message, edit the WIN.INI file using any text editor and remove the line that the error is occurring on or place a semicolon in front of the line to comment it out. It is advisable to troubleshoot the problem one step further and determine what is wrong with the device that is not responding.

Windows 95

Windows 95 provides some common error codes that can be used to help troubleshoot a system problem. Many times these error codes are your only suggestion as to the cause of a problem. Knowledge of these common error codes can only prove to speed along the troubleshooting process. The common error messages that discussed here are:
Missing or Corrupt HIMEM.SYS
No Operating System Found
Safe Mode
VFAT Initialization Failure
Bad or Missing COMMAND.COM

Missing or Corrupt HIMEM.SYS

Like Windows 3.x, Windows 95 requires that HIMEM.SYS be loaded for the operating system to function correctly. Windows 3.x is dependent on the CONFIG.SYS file correctly loading HIMEM.SYS. Windows 95 automatically loads HIMEM.SYS from the C:\WINDOWS\COMMAND directory prior to processing the CONFIG.SYS file. There are two possible problems that could cause you to receive the "Missing or Corrupt HIMEM.SYS" error in Windows 95. First, if the file is actually deleted from the C:\WINDOWS\COMMAND directory, and second, if there is a line in CONFIG.SYS referencing another version of HIMEM.SYS. If there is such a line, simply delete it.

No Operating System Found

The message "No Operating System Found" indicates that there is either something wrong with the hard drive of the system or the boot files have been corrupted. Running the Windows 95 setup program should fix any problems related with the boot files being corrupted. If you are unable to write to the hard drive, the problem could be anything from a bad cable to a bad hard drive.

Safe Mode

Any time Windows 95 encounters an error, it automatically starts the system in safe mode. Safe mode is a special diagnostic mode that does not load most of the drivers normally loaded and loads a standard VGA display driver. Safe mode provides a method for you to change system settings in many cases where incorrect settings have rendered the system useless. For example, in the event that an incorrect video driver was installed, safe mode would allow you to correct it, and return the system to its normal functionality.

VFAT Initialization Failure

VFAT initialization failure occurs when the system is unable to initialize the driver that controls the file system on the drive. The first step in attempting to correct this error would be to reboot the system, press F8 when the "Starting Windows 95" message is displayed, and choose "Safe Mode Command Prompt Only" from the list provided. From this command prompt ,the SCANDISK utility can be run to attempt to fix physical drive problems. If SCANDISK is unable to fix the error, rerunning Windows 95 setup should correct the problem.

Bad or Missing COMMAND.COM

Windows 95 expects that COMMAND.COM will be installed in the C:\WINDOWS\COMMAND directory. In the event that COMMAND.COM is not located in the C:\WINDOWS\COMMAND directory, you should replace it. COMSPEC being set in the CONFIG.SYS file to a directory where COMMAND.COM is not located could cause the problem. In addition, if a manual path statement has been added to the AUTOEXEC.BAT that does not include the C:\WINDOWS\COMMAND directory, this could cause the problem. If none of these possible difficulties exist, rerunning Windows 95 setup should correct the problem.

Correcting a Startup or Boot Problem

There are many startup or boot problems that can occur. The most common and usually easiest solution to these problems is to rerun the setup utility that shipped with your operating system. The setup utility should correct any problems you are having.

Creating an Emergency Boot Disk with Utilities Installed

Windows 95 provides a simple method of creating an emergency boot disk Follow the procedure outlined in Exercise 12-1.
Exercise 12-1 Creating an Emergency Boot Disk
  1. Insert a floppy disk into your floppy drive
  2. Click the Start button and choose Settings | Control Panel.
  3. Double-click the Add/Remove Programs icon.
  4. Select the Startup Disk tab on the far right.
  5. Click on the Create Disk button.
Windows 95 can easily create a startup disk that can be used to diagnose and fix problems in the event of Windows 95 not working properly

Recognizing Windows-Specific Printing Problems

The Windows printing subsystem simplifies the task of printing a great deal for both the user and the applications authors. Unfortunately, with the standardized Windows printing system comes some common problems that could occur. These problems are:
Print spool is stalled
Driver is set for bi-directional mode with a uni-directional cable
Incorrect/incompatible driver for printer
Printer port not setup correctly in device manager
Printer is not set to print to correct port

Print Spool Is Stalled

The print spooler can stall itself in order to hopefully prevent the user from losing a print job. In the event that the print spooler does become stalled when it should not be, the problem can be solved by clicking on the File menu from the Printer Properties and selecting Restart Printing.

Driver Is Set for Bi-Directional Printing/User Is Using a Uni-directional Cable

Some of the newer and more advanced printers have the capability of using a bi-directional mode, meaning that the printer is able to talk back to the computer. This can be extremely useful because it allows the printer to send the user exact error messages that are displayed on the workstation, and helps the spooler to avoid print spooler stalls. In the event that you are unable to communicate with a bi-directional printer, your first step should be to turn off bi-directional printing in the Printer Settings tab. If the printer works after bi-directional support is turned off, you can either leave it that way and be happy, or replace the cable with a bi-directional capable cable. Also note that bi-directional support could be turned off in the systems BIOS (consult the system’s manual for details on how to correct this problem).

Incorrect/Incompatible Driver for Printer

It is extraordinarily important to verify that the driver that you are using to print to your printer is the correct version for your printer. The driver should either be specifically manufactured for the printer you are using, or should be listed as a compatible driver by the printer manufacturer. If you need to get a new driver for the printer, either visit the manufacturers Web site or call their technical support team.

Printer Port Is Not Set Up Correctly in Device Manager (ECP, EPP, Standard)

Windows 95 requires that the port for a printer be installed (installed correctly, to be specific). Windows 95 usually detects and installs ports correctly, but may install a port as Standard when it should be installed as ECP. To correct this problem, use the Add New Hardware Wizard from the Control Panel to add a new port. If after adding the new port you are still having difficulties, you may want to consult your system’s documentation to verify that the port is set in the correct mode in the system’s BIOS.

Printer Not Set to Print to Correct Port

Having a printer set to the wrong port is undoubtedly one of the most easily solved problems that you can encounter. To change the port that a printer is set to print to, open the properties dialog box of the printer in question, which is shown in Figure 12-2. Next, select the Details tab and change the port setting to the correct one.

An incorrect port setting can be changed from the Details tab of the Printer Properties dialog box

Common Problems and Causes

There are some common problems that occur frequently on Windows systems. Whenever one of these problems occurs, it is important to remember that your system may have been rendered in a less-than-optimal state. Even though the system appears to be functioning properly, it may continue to have difficulties. The best solution for most problems is to simply reboot the system.

General Protection Faults

General protection faults (GPFs) occur frequently when an application performs an operation that Windows does not normally permit to happen. GPFs can be caused by nearly anything, and can almost be considered a catchall for errors. If an application causes a general protection fault, you should restart the system at your earliest convenience. In many cases, the problem is solved by a simple reboot. In the event that the problem is not solved, you should reinstall the application. If after reinstalling the application the error still continues, it is advisable to contact the program vendor’s technical support.

System Lock Up

Applications can easily lock up or hang a system for nearly any reason. In the event that you encounter a lock up, you should simply reboot the system. If lock ups continue, you might want to run scandisk and defrag on the system. If after running SCANDISK and DEFRAG, the lock ups still continue, reinstalling the application where they most frequently occur should take care of the problem.

Operating System Will Not Boot

The operating system not booting could be caused by nearly anything, although it is rather rare. Rerunning that operating system’s setup program should solve any problems.

Application Will Not Start Or Load

In the event that an application does not start, you should first restart the system to attempt to correct the problem. If restarting the system does not solve the problem, reinstalling the application usually does.

Cannot Log On To Network

Most times that a system is unable to log on to the network are caused by external problems such as a broken cable or problem in the wiring closet. Another popular cause is a bad network card. The first course of action that should be taken is to reboot the system. If the problem still continues, removing and reinstalling the network drivers usually takes care of any problems. If the problem is still not solved, it is best to start troubleshooting the network for other difficulties, and determine if the problem is with the particular workstation.

DOS- and Windows-Based Utilities and Commands/Switches

There are many different utilities that are provided with both DOS and Windows 3.x/Windows 95 that help in the diagnosing, and in some cases solving, most problems.

DOS

DOS provides some very useful tools that allow us to do anything from gather information about the system to reorganizing the file locations on the hard drive in order to improve performance. The DOS-based tools examined here include:
MSD.EXE
SCANDISK.EXE
DEFRA.EXE
MEM.EXE
EDIT.COM
FDISK.EXE
ATTRIB.EXE

MSD.EXE

MSD, Microsoft Diagnostics, is a utility that provides a great deal of information about the system and is demonstrated in Figure 12-3. MSD is most useful in determining what the system has installed in it, such as memory and hard drives. This information is available in other forms, but not all in one group as MSD presents it.

Microsoft Diagnostics provides a good survey or the system’s features in one easy-to-read format
Exam Watch: The Microsoft Diagnostics utility can be used to provide information about the system. This information can be valuable in determining if a workstation is capable of being upgraded

SCANDISK.EXE

SCANDISK is a utility that can be used to check disk drives for errors and, when passed the /f switch, fix them. Many reoccurring problems can be solved by running the SCANDISK utility.

DEFRAG.EXE

DEFRAG is a utility that can be used to reorganize a hard disk drive. DEFRAG reorganizes the drive into a fashion that it feels is logical, which usually results in improved system performance.

MEM.EXE

MEM.EXE provides information about the memory that is installed in the system, and what it is being used for. Passing the /c switch displays information on what programs are using the memory, and how much memory they are using. Passing the /f switch provides information about free memory in the system. Many times there is too much information presented on the screen, and you are unable to read it. To alleviate this problem, passing the /p switch pauses after each page of information is displayed. Simply running MEM.EXE, as Figure 12-4 shows, tells how much memory is installed in the system and how much of that is free.

MEM.EXE can be used to provide information on the memory that is installed in the system and how much of it is available

EDIT.COM

EDIT.COM is a simple ASCII text editor. It can be used to modify system files such as AUTOEXEC.BAT and CONFIG.SYS. It is simple to use and provides a basic GUI and mouse support if a mouse driver is loaded.

FDISK.EXE

FDISK.EXE can be used to create and delete partitions on the system’s hard disk drives. Be warned that FDISK.EXE makes changes that are permanent and could easily render the system unbootable and make all data on the hard drives inaccessible. Use FDISK with care and ensure that all your data is backed up. FDISK, as shown in Figure 12-5, provides an easy-to-use menu-driven interface.

FDISK.EXE can be used to create and delete partitions on a hard disk drive























FDISK/MBR can be used to replace the Master Boot Record with a backup copy. This may become necessary if the Master Boot Record becomes infected with a virus. FDISK/MBR is not destructive in any way unless the computer has a third-party boot program installed. These programs are found frequently in older systems with hard drives larger than 540 megabytes installed in them.

ATTRIB.EXE

ATTRIB.EXE is a utility that can be used to change the attributes of a file or group of files. Attributes include Read-Only (r), Archive(a), Hidden(h), and System. To turn on attributes, add a plus-sign in front of the letter corresponding to the attribute. To turn off an attribute, add a minus-sign in front of the attribute. To process all of the files in subdirectories, add the /s switch.
To make the file . . .I would use the command . . .
C:\AUTOEXEC.BAT hidden and read-onlyattrib c:\autoexec.bat +h +r
C:\AUTOEXEC.BAT unhiddenattrib c:\autoexec.bat –h
C:\AUTOEXEC.BAT system, read-only, not hidden, and archiveattrib c:\autoexec.bat +s +r -h +a
All files in the C:\INFO directory read onlyattrib c:\info +r
All files in the C:\INFO directory and all subdirectoriesattrib c:\info +r /s

Windows-Based Tools

Windows provides some additional tools and some extensions of the DOS-based tools. The tools discussed here are:
SCANDISK
DEFRAG.EXE
Device Manager
Conflict Troubleshooter
SYSEDIT.EXE
Control Panel
System General Properties

SCANDISK

Windows SCANDISK, which is shown in Figure 12-6, is nearly exactly the same as the DOS-based SCANDISK. It is capable of detecting and fixing most drive corruption problems that could exist. SCANDISK is capable of fixing errors that it finds without any special parameters, unlike the DOS-based SCANDISK, which requires a /fix switch in order for it to be able to fix problems it finds. SCANDISK operates more efficiently if you close all application prior to running it.

Scandisk can be used to detect and fix most drive corruption problems

DEGRAG.EXE

Windows DEFRAG is capable of reorganizing the layout of hard disk drives in the same fashion that the DOS-based DEFRAG does. DEFRAG runs more efficiently if all application are closed prior to running it and after SCANDISK has been run on the drive.

Device Manager

Device Manager is a utility that is provided with Windows 95. Device Manager lists all of the devices that are installed in the system and their properties, as shown in Figure 12-7. Device Manager can be accessed by double-clicking on System in the Windows 95 Control Panel and selecting the Device Manager tab.
Device manager lists all of the devices that are installed in the system and their properties

Conflict Troubleshooter

Conflict Troubleshooter is a utility that is provided with Windows 95 that can be used to help resolve conflicts between two or more devices. Conflict troubleshooter automatically starts whenever the system starts and detects a conflict.

SYSEDIT.EXE

SYSEDIT.EXE, the System Configuration Editor, is a utility that is provided with both Windows3.x and Windows 95. SYSEDIT.EXE, which is shown in Figure 12-8, helps you to easily edit the system configuration files.

SYSEDIT is a tool that enables you to edit the system configuration files from one easy interfaceThe files that SYSEDIT.EXE enables you to edit are:
MSMAIL.INI
PROTOCOL.INI
SYSTEM.INI
WIN.INI
CONFIG.SYS
AUTOEXEC.BAT

Control Panel

The Control Panel, shown in Figure 12-9, is a utility that can be used to change the settings of the system. By double-clicking on any icon that is listed, you can change the properties that are associated with whatever that icon represents. Note that each system has some core icons such as "Add New Hardware" and "Add/Remove Programs," but icons that are available varies by what is installed on the system.


The Control Panel provides a method of modifying the configuration of the computer
 

System General Properties

System General Properties provides information about the computer such as the version of the operating system, the processor that is installed on the computer, and the amount of memory that is installed. The System General Properties can be accessed by double-clicking on the system icon in the Control Panel.

Registry Editor

The Windows 95 Registry Editor, as shown in Figure 12-10, is the most powerful tool in Windows 95. Be extremely careful when using the Registry Editor. Nearly any setting of the system can be changed within the Registry Editor. You will never be warned if a change you are making could negatively affect the system.

Figure 12-10: The Windows 95 Registry Editor is capable of changing nearly setting on the computer
EXAM WATCH: The Windows 95 Registry Editor can be used to change any of the settings of the system that are stored in the registry. The Registry Editor can cause irreparable harm without any warning.

Installing and Configuring DOS Applications, and Potential Problems in Windows 95

Most DOS-based applications can simply be run from within Windows 95 without any difficulties. There are some cases where it is beneficial to make some changes to the configuration of these applications.

Setting Memory

Many DOS programs require that a specific amount of memory be available to the program. Even though there is ample memory available, the programs may attempt to directly access the memory, in which case they can be led to believe there is no memory available. To correct this problem, open the properties for the shortcut to the application that you are dealing with and select the Memory tab, as shown in Figure 12-11. Adjust the memory configuration to the amount the application requires.

The Memory tab of the Shortcut Properties dialog box can be used to specify how much memory is given to application

Setting Screen Size

Some applications can be difficult to use when they are run in a windowed mode. To change the screen size that an application is run at ,select the Screen tab of the Shortcut Properties dialog box, shown in Figure 12-12. From the Screen panel, adjust the initial size to whatever you desire. Remember that a full-screen application can always be forced into windowed mode by pressing Alt-Enter.

The Screen tab of Shortcut Properties dialog box can be used to specify the display mode in which an application starts

Determine Whether To Display The Win95 Toolbar

Some applications do not perform well when the Windows 95 Toolbar is displayed. In some cases of applications that were not specifically designed for use with Windows 95, the toolbar may cover vital parts of the application. To prevent the toolbar from displaying, uncheck Display Toolbar from the Screen panel of the Shortcut Properties dialog box.

Enable/Disable Dynamic Memory Allocation

Enabling dynamic memory allocation permits Windows 95 to automatically give an application memory when it needs it and take memory away when the application is not using it. This is good in most cases, but some older applications expect a certain amount of memory to be there, and it may cause problems when it is not. To disable dynamic memory allocation, uncheck Dynamic Memory Allocation from the Screen panel of the Shortcut Properties dialog box.

Illegal Operations Error

Illegal operations, in short, occur when an application attempts to access hardware or memory directly. Windows 95 limits the direct access of any hardware by applications and will repeatedly cause illegal operations in the event that the application attempts this. The best solution to an application that frequently causes illegal operations errors is to force the application to run in MS-DOS mode. Applications can be forced to run in MS-DOS mode by clicking on the Advanced button from the Program panel of the Shortcut Properties dialog box, as shown in Figure 12-13. If MS-DOS mode is then checked, the application automatically enters MS-DOS mode (after warning you to save all your work in other applications).

The Advanced Program Settings dialog box can be used to force an application to run in MS-DOS mode

Application May Quit and Windows 95 Stops Functioning

In the event that an application stops functioning, it can frequently hang the entire system and cause the system to appear to be non-functional. Follow the procedures in Exercise 12-2 to remedy this problem.
Exercise 7-1 Closing a Program That Is Not Responding
  1. Press Ctrl-Alt-Del to invoke the Close Program dialog box.
  2. Choose the application that is not responding from the list of current applications.
  3. Click the End Task button. This returns the system to a functioning state in many cases.
  4. If after a few minutes the system does not return to its previous stability, reboot the system. This should return it to normal operation.

Viruses and Virus Types

Viruses are unfortunately something that have become a part of everyday computer life. Any device that can receive data from another device is susceptible to being infected with a computer virus. Viruses are very dangerous problems that plague computing today. They can cause anything from the extreme data loss to the annoying message that pops up every few minutes. Viruses can come from nearly anywhere, but are usually created by someone with malicious intentions. Purchasing and installing a good virus scanning/removing application is the best solution the virus problem.

From the Field

The Cost of Viruses To the World

One can only speculate what goes on in the mind of a demented virus creator. Do they think they are being clever? Funny? Brilliant? What? Perhaps in their own little worlds, they are achieving some kind of goal. But in the real world, they are costing the computing society much more than they can comprehend.
Lost corporate time trying to fix these as well as rebuilding that which they destroy is almost incomprehensible. A destructive virus costs companies collectively more than the biggest armed bank heist in history. I wonder if the creators of these know what their creations are costing people. In the near future, the laws should change on these and make them severe felonies.
Money is not the only factor in this damage. Many users out there are not sophisticated enough to be armed with the absolute latest virus checkers, if they are even armed at all. I think of an 80-year-old who is writing his life story and gets zapped by one of these and Bam!, down the drain. Or even for those who are sophisticated enough to have virus checkers, they may not update them regularly.
Viruses are bad news. They can totally destroy your data as well as hardware. Most of you have probably spent tons of time configuring your system and you would hate to have to re-install everything. The moral: Make sure that you and those whose PCs you work on have the latest patches from a reputable virus prevention software company.
— By Ted Hamilton, MCP, A+ Certified

What are Viruses?

A virus is any program that is designed with the intention of doing harm to a computer. Viruses can result in anything from damaging your computer’s hardware to making a siren blare every day or two. The most common result of viruses is a loss of data of some sort. If your system appears to be operating in a manner that you don’t expect it to be, you should scan it for viruses.

Sources

Viruses are in most cases created by persons with the intention of doing harm to other persons’ computers. On some occasions, viruses can be created by an unintentional error of a programmer, although this is extremely unlikely.

Spread

Viruses can be spread whenever a computer makes contact with another computer, directly or indirectly. For example, if you download a file from the Internet, the file could be infected with a virus, which could in turn infect your computer. On the converse, you could infect your computer by opening a file your friend gave you on a floppy disk.

How To Determine Presence

In most cases, the presence of viruses is fairly difficult to detect without a virus detection application. Virus detection applications are available for sale, and are made by many different software companies.

Removal

Most virus detection packages include the ability to remove the virus from the system. By running the virus removal software, most viruses can be removed. In the event that the software is unable to remove the virus, using the FDISK.EXE and FORMAT.COM utilities from a known virus-free boot disk will remove any viruses.

Prevention

Many of the popular virus detection applications also have the capability to scan the system for viruses and detect/clean any that it finds. In addition, some of the more progressive software can automatically check each file as it is opened, and scan any files that are downloaded as they are downloaded.

Types of Viruses

There are many different types of viruses that all ultimately cause harm to the overall computer, but exhibit some individual, specific traits. The virus types discussed here are:
Boot Sector Virus
FAT Virus
Memory Virus
Macro Virus
CMOS Virus
Hoax Virus

Boot Sector Virus

A boot sector virus stays resident by infecting the boot sector of the computer. Each time the system is booted, it is re-infected from its own boot sector. Any time a floppy disk is inserted into the drive, the floppy’s boot sector is infected. If a machine is booted from or even if an infected floppy disk is left in the floppy drive when the system is rebooted, that computer will then be infected.

FAT Virus

A FAT Virus infects the File Allocation Table of a hard drive. FAT viruses are usually not spread by themselves and are carried along with other viruses. FAT viruses usually cause a loss of files that are on a hard drive, and are usually difficult if not impossible to recover from.

Memory Virus

Memory viruses are viruses that execute and stay resident in memory. Memory viruses usually do not spread themselves, but are carried along with other viruses.

Macro Virus

Macro viruses are viruses that attach themselves to documents in the form of macros. These macros can infect all of the other macros on the system, and all new documents created on the system. Macro viruses most commonly infect Microsoft Word and Microsoft Excel documents, but have the possibility of showing up in any application that includes the ability to create macros.

CMOS Virus

CMOS viruses are viruses that make themselves resident in the CMOS of the computer. These viruses are one of the most difficult to remove. CMOS viruses frequently cause harm to the hardware of the computer.

Hoax Viruses

Hoax viruses are just that, hoaxes. The most common hoax virus began with the title of "Good Times, " and has resurfaced under many other names. These virus hoaxes are usually sent as e-mail warnings not to open any e-mails of these titles. In the event that you receive any email similar to this please notify the sender that it is a hoax, and ignore it.

Certification Summary

In this chapter, we have examined many of the common errors that you can receive while working on a computer running DOS, Windows 3.x, or Windows 95. In addition, we have detailed many of the causes and solutions of these problems and discussed some of the common tools that can be used to repair them.

Two-Minute Drill

The SETVER utility can be used to make applications think that they are running on the version of DOS that they want to be running on.
The most common cause of the "Error in CONFIG.SYS line XX" (where XX is a number) error is a missing file.
Both Windows 3.x and Windows 95 require that the HIMEM.SYS driver be loaded in order to access High Memory.
If Windows gives you a "Unable to initialize display adapter" error, you should use the Windows setup utility to change the adapter type.
Any time Windows 95 encounters an error, it automatically starts the system in safe mode.
The most common and usually easiest solution to startup or boot problems is to rerun the setup utility that shipped with your operating system.
The message "No Operating System Found" indicates that there is either something wrong with the hard drive of the system or the boot files have been corrupted.
General protection faults (GPFs) can be caused by nearly anything, and can almost be considered a catchall for errors.
The Microsoft Diagnostics utility can be used to provide information about the system. This information can be valuable in determining if a workstation is capable of being upgraded.
DEFRAG is a utility that can be used to reorganize a hard disk drive.
ATTRIB.EXE is a utility that can be used to change the attributes of a file or group of files.
The Windows Device Manager lists all of the devices that are installed in the system and their properties.
Be extremely careful when using the Registry Editor, as nearly any setting of the system can be changed within it and you will never be warned if a change you are making could negatively affect the system.
Enabling dynamic memory allocation permits Windows 95 to automatically give an application memory when it needs it and take memory away when the application is not using it.
Illegal operations, in short, occur when an application attempts to access hardware or memory directly.
The best solution to an application that frequently causes illegal operations errors is to force the application to run in MS-DOS mode.
A virus is any program that is designed with the intention of doing harm to a computer. The best defense against virus infection is to purchase a good virus scanning/removing application.
Memory viruses are viruses that execute and stay resident in memory.
A boot sector virus stays resident by infecting the boot sector of the computer.
FAT viruses are usually not spread by themselves and are carried along with other viruses.
Macro viruses are viruses that attach themselves to documents in the form of macros.
CMOS Viruses are viruses that make themselves resident in the CMOS of the computer and are the most difficult viruses to remove.
The most common hoax virus began with the title of "Good Times, " and has resurfaced under many other names.