Backups are essential, but are only one part of the deal.

What happens when you backup a drive that already contains malware, or that contains a defective program or other component that you just hadn't discovered when the backup was made?

In the present case, we don't know why it was decided that the two "problem files" needed to be removed, but it's quite likely that they have been present for some time and would also be contained in any backup likely to have been made.

We also have learned that the computer in question can't be booted to Safe Mode. Since the user has never tried to boot to Safe Mode we don't know when that failure occured; but the condition quite probably has been present long enough^** to have been backed up by anyone who kept their backups current.

In this case, restoring from a perfect backup would solve absolutely no existing problem. The computer quite probably still would not boot to Safe Mode, and the unwanted files would still be present after restoring from any backup likely to have been made.

^** The causes for inability to boot WinXP to Safe Mode that are described by Microsoft's Knowledge Base all relate to incompatible drivers at the time of installation of SP2. SP2 was released approximately two years ago, so it's quite likely that this computer has not been able to boot to Safe Mode since then. Any backup within the past two years would contain the error, and any backup more than two years old would be obsolete, since it wouldn't "be SP2" which is required for support of the system.

John