If you're running Windows 2000 or Windows XP, use the system file checker to search for corrupted files. Log into the system as Administrator, and simply click Start > Run and type "sfc /scannow" without quotes. You may need to provide a copy of the original installation CD, and a copy of the latest service pack installed on your system so corrupted files are replaced with the latest versions. If this fails, you should try doing a repair installation using your startup disks.
This was first published in June 2004