Over the last 24 hours lots of friends have been emailing and phoning about this “terrible virus”, so be aware of this before doing anything to your computer:

http://www.symantec.com/avcenter/venc/data/sulfnbk.exe.warning
edit: yet another link not working properly - this was the original, if you want to cut'n'paste -
http://www.symantec.com/avcenter/venc/data/sulfnbk.exe.warning.html

Dear maverick: The virus is a hoax. I found this at Symanted

Results for: sulfnbk.exe

SARC Write-up - SULFNBK.EXE Warning
The following hoax email has been reported in Brazil. The original email is in Portuguese; it is followed by an English translation. CAUTIONS: This particular email ...

Yes, that's the one Bill. So if you get a message from a friend telling you to start deleting minor Windows files, point them in that direction (which inlcudes advice on how to repair any damage!)