Computer security Question:

On the NT 4.0 CD-ROM there are a utility called rollback.exe that will corrupt your system if run. It is not intended for end-users, but someone slipped and the tool is now out on many users systems.

Without any sign of warning, rollback.exe will remove all system registry entries, which in turn will leave the system in a state where there are not easy way to recover. One have to grab the emergency repair disk and do a restore from the latest backup.