If this is still an issue, I've had an extremely high rate of success with "Malware bytes Anti-Malware" which seems to be a newer one on the scene.
http://www.malwarebytes.org/mbam.php
Otherwise, Spybot, Ad-Aware, and HijackThis are oldies but goodies, and all worth attempting.
If you have access to another PC with known, up-to-date AV (in my opinion, F-Secure is one of the best. 30 day free trial. f-secure.com)
Pull the hard drive from the offending PC, and install it as a "slave" in the "clean" PC. Then boot up, and use the good AV program to scan the bad drive. scanning in this fashon works because the programs (virus) on the bad drive never get a chance to run, and therfore can't get into the memory, and set up their own defences. Once I do the scan this way, I typically re-install the hard drive in the other PC, and run spy-bot in safe mode, on each individual profile. (hopefully you only have one "user" on that PC. that will simplify this significantly. although remember, when you boot in safe mode, you'll also have an "administrator" option.)
Clear as mud? Great! Yes, I used to do this for a living. Now I fix phones. much easier. Our new IP phones however, have the ability to execute XML code. this scares me.