Download Adaware it's free install it and scan machine with it and let him clean all malware .Hope this help You.
That is completely wrong- adaware scans the entire hard drive for adware and spyware: the exact thing that would change your homepage and keep it changedenyalius said:Ok adaware only works on ad popups, and stuff like that. Has nothing to do with the problem that he is having.
The problem you are having sounds a lot like a virus (trojan or worm) you can try one of the online scanning websites see if they work but if not you may have to buy the virus software to get rid of the virus.
Friend had the same issue, with a very unwanted homepage (had some porn on it i believe if i remember correctly) it was a virus, he reinstalled windows but you should try a virus scan first