Chances are something winth-in Windows is corrupt. You could trying "System Restore" if your running Windows ME or XP. Goto Start > Programs > Accessories > System Tool's > System Restore. Choose the option to restore to an earlier date and you'll get a screen with a calander on it. Any date in bold is a restore point. If you click on the date it will show you what was installed at the time.

Chances are though that it won't work as system restore is as much use as a car with no engine.

I'd recommend you back up anything you want to keep format your hard drive and re-install Windows. If you get the same problem after doing that i'd say you have a faulty piece of hardware.