What is the Hard Drive?
The hard drive or disk drive is the long term storage for programs, data, pictures, music, videos, etc.
What is chkdsk?
Chkdsk is a standard, built-in windows tool used to find and fix disk errors caused by faulty installations or power failures or hard drive issues.
Windows XP
Click: Start -> Run
type: 'chkdsk c: /f' without the quotes, and click: OK
When your asked: 'Would you like to schedule this volume to be checked the next time the system restarts? (Y/N)', choose Y
Restart your computer
NOTE: this could take a long time [ie., many minutes] to complete
Windows Vista and Windows 7
Click: Start -> computer
Right-Click Disk and choose properties, choose tools, and click Check now