Ran across this resurrecting a college coed's barely functioning PC.
After using Spybot, Adaware, and Hijackthis to remove the obvious and dorking the registry where not, the darn thing would not let go.
The final symptom was every google search returned a pop behind window, and the first google results page was a forged list of sponsored links. Very clever, very annoying.
Here's a link to a utility that removed the final piece. Thanks Merijn.