God Tyrael... again!? I second Cletus! Except for the cheap part, it's okay to be a cheap bastard. I know I am.
If it keeps coming back, you're not getting rid of everything, you're still missing something. Either that or it replaced a system file with a different version to suit it's purposes. When you try getting rid of this crap, do it in safe mode, stop it from running if it is, delete it from the registry, and hunt down it's files. Also, don't forget to run scans. ^^
Spyware doctor? Are you serious? Well, that's going to get rid of the spyware and shit... but not the virus... which will likely still run, and still be in the registry. What anti-virus are you using?