Scan Disk

Click on Start
Click on Programs
Click on Accessories
Click on System Tools
Click on Scan Disk

Scan Disk will now load

Make sure "Drive C" is highlighted

Make sure there is a check by "Automatically Fix errors"

Click on Start

Scan Disk will start scanning your harddrive

Scan Disk will finish

Click "Close"

Congratulations! You have successfully run a Scandisk!

A thorough scandisk should also be run periodically.
I like to run a thorough scan disk once a month.

To run a thorough scan disk, place the dot by "Thorough", instead of "Standard".