I've seen this kind of thing before, typically it's a result of surfing pr0n (I'm not judging
). The first thing I'd do is scan with Adaware and/or Spybot S+D.
After that if you still can't get rid of it you're gonna have to search for help on google. Sorry man I know your pain, I've had to reformat a couple of times get rid of this kinda shit. Then I switched to Opera for surfing "those sites."