hijacked!

My neighbours computer has been hijacked. She asked me to have a look at it. I tried tools, internet options, and changing home page.nope. Tried tools, inter opt. programs. reset web settings. worked. but when she went offline and then on again, it was still hijacked. I was reading about hijack this but I am a little nervous of deleting something that I am not suppose to. Is there something I should look for? She had not been doing the xp critical updates, I downloaded 17 so I am sure that did not help being left wide open. Any help would be appreciated. Thanks in advance