Screensaver and background tabs missing

If this just happened you can try running a system restore point to a recent date when all was well. Sometimes works, sometimes doesn't, but always worth a try.

Because you had or removed viruses you more than likely need to try to do a XP repair install. This will attempt  to fix any missing or damaged system files.

As always it is a good idea to back up your system of any importan data you want to perserve. then read the info in this LINK