Virus??

Hi!
Can someone HEEELP, everytime I start up internet it start up with a startpage called “about:blank” I cant removed it from my computer. I can change startpage but next time I go in its the same again. When I use Yahoo it change page when Im in and look at my mail. Please help me get it out from my computer.

It is a Hijacker. Please read this:
http://forum.avast.com/index.php?board=4;action=display;threadid=5373
install update the mentioned Spybot/Adware/CWshedder. If that does not fix your Problem, post a hijackthis log