Spyware/Virus or something else connecting to a lot of SMTP servers

"Once your computer is infected, it is hard to know if everything is removed - it is possible to trick the virus scanners if the malware is intelligent enough.

I recommend you use Microsoft / Sysinternals Autoruns and basically delete anything that you think could be malicious.

If this doesn't work, as you have already scanned for malware (on top of that, I currently recommend Spybot Search and Destroy as well as Microsoft Security Essentials), the next thing is simply to reinstall Windows."