I had that happen to me, and i don't know too much about computers. I went to a website called
www.computercops.biz
went to the forums (the hijack-spyware forum) they make you download a program called hijackthis (its free), and you run it and cut and paste a log and they'll tell you what to do. it took a while, but if you are patient they are very helpful and had my computer better in no time.