Try running a couple of spyware scans...
Here's some good freebies...
Ad-Aware __(FREE) Spybot - Search & Destroy __(FREE) AVG Antispyware (formerly Ewido)
I have all 3 installed, if one doesn't get the other will...
If you still can't get rid of it, try one of these sites, these guys will help you out...
Bleeping Computer - Computer Help and Discussion SpywareInfo Forum FAQ - SWI Forums