When something goes wrong, the Windows System Restore feature that debuted with Windows Millennium Edition offers users the ability to roll their systems back to a kinder, gentler time. Making changes to the system, such as installing or uninstalling a program, cause the feature to create a checkpoint. Unfortunately, if you are trying to rid your machine of a virus infection or spyware, System Restore can be your enemy. Virus scanners cannot clean infections from restore points, making reinfection possible. The same can happen if you do a system restore after running an anti-spyware utility, with objects reappearing after a scan-and-delete sweep. This is why all anti-virus vendors recommend disabling System Restore before attempting to clean a system.