Try this:
http://www.lavasoft.de/software/adaware/
And this:
http://www.safer-networking.org/en/mirrors/index.html
Anti-Spyware + Anti-Adware
They help..
Oh, and try getting a proxy
http://www.hidemyass.com/
And if all else fails, reformat... Its good for you computer once in a while anyway.