Tell ya what - lets see a
HiJackThis scan log. Be sure to install it to and run it from a folder of its own either directly on your root drive or in your Programs folder, not from your desktop or any temporary foldr. When you run it, do so with no other browsers or windows open, and with no other applications running. or an overview of what you might expect, and for more detailed instructions regarding HiJackThis, see
THIS TOPIC.
Don't worry too much about the whole procedure outlined there; right now, just get us a HiJackThis log, and we'll see what we've got.