use Adaware and Spybot Search and Destroy be sure to update them to get latest data files . If those don't clean it out. go to start, run, regedit . click edit, then find, type in the address to search for it, F3 will find next instance , every one you see, edit it to what ever you want to use as homepage . this way takes time but it'll clean it out.. oh and be careful when you use regedit.
hope this helps