Moosetick - 5:34 pm on Apr 26, 2006 (gmt 0)

Most PCs now come with a restore CD that will wipe the drive clean and reinstall everything to the way it was when the computer was sold. Check to see if you have that. Usually you just boot to that CD and go through a simple menu system confirming that you know you are about to restore the OS.

Be warned that when you do a restore, all your data will be erased. Therefore do a verified backup of your data before you start the restore process.