Are you running Spybot? If not, you should be. The Spybot folks are seriously dedicated to destroying malware. They are free, although they do accept donations.
You can download Spybot for free here:
http://www.spybot.com
If that does not fix it, post your specific problem in the spybot help forum. Only certified computer geeks are able to post replies there, so you won't eff up your compo.
http://forums.spybot.info/forumdisplay.php?f=22
Read this thread first:
http://forums.spybot.info/showthread.php?t=288
After you have done that download Hijack This. Only use Hijack This to create a log. Do not use it to fix problems, even though it has that option. Again, do not use Hijack This to try to fix your problem.
http://www.trendsecure.com/portal/en-US/tools/security_tools/hijackthis/download
After you download and install it do a system scan and check the "save a logfile" option. Copy and paste the logfile into a new thread in the spybot forum. The geeks there might take a day or two to answer, but their advice will be tight. And they will keep working with you until you get it fixed. Give that a try.