seen this problem dozens of times. HijackThis will solve it. just don't delete any of the services unless you know what you're doing. if you start messing with those, you run the risk of having to reinstall the OS.
http://www.download.com/Trend-Micro-HijackThis/3000-8022_4-10227353.html
http://www.download.com/Trend-Micro-HijackThis/3000-8022_4-10227353.html