Here's a couple things to try:
1. Boot in to "safe mode with networking". Run your web browser and visit Ewido's web site
for their free scan. Ewido does an excellent job of clearing out spyware that anti-virus may miss.
2. Pick an online anti-virus scan service and have it check our system. I often use the scanner at PcPitstop
but any will do. The reason for doing a scan from an external site is that some trojans & viruses can trick your installed anti-virus software.
3. Download Hijackthis
. The program generates a list of what runs when you start Windows. You can then post the log to one of several foums and often get an instant response for what to disable.