Try following these instructions:
http://forums.spybot.info/showthread.php?t=1958
In principle you always do this after an infection:
Disable/disconnect any network connectivity;
Start up in Safe Mode (Hit F8 -> into menu while booting Windows up);
Use regedit to remove all references to infection-carrying code;
Delete infection-carrying code (may be any .EXE .DLL etc file or files).
I know, the hard bit is to decide which files and references to remove! For some infections (rootkit type) a separate utility is required.
The basic tools are msconfig (built-in with Windows) and HijackThis
http://www.majorgeeks.com/download3155.html .
After repair you must APPLY ALL SERVICE PACKS immediately. It's a very good idea to have Service Packs on a CD. They can be loaded as independent (administrator) packages from the MS site.