While you may not want to do this, you could reinstall the OS.
If that is too drastic, see what starts up @ boot time, and disable everything.
You can check with autoruns
http://technet.microsoft.com/en-us/sysinternals/bb963902.aspx (free)
Then, enable them one by one to see which one causes this malware to come back to your system.
If that don't work, then time to disable any NON MS service and enable them one by one again, to see which one is at fault.
It also is a good idea to boot with a clean copy of windows, with only malware detectors on it, then boot with that, and then point it to your OS drive for a deep scan.