I am just guessing, but you probably have a virus.
I just got through all of this myself.
Check the recent posts, you will see mine, as I was asking about viruses from online casino's, etc.
I got rid of the virus, but my friend did it for me. He had to clean out my entire system and start from scratch. It was a real pain in the ass.
He recommended that I get Panda Internet Security 2006. He said that this is one of the best out there. It costs $80 for the year. It comes with Internet protection, anti-virus, spyware, and firewall all in one.
I just hope it works now. I had Norton, and spysweeper, but I still kept getting these viruses. Norton can blow me. I am done with them.
I think I am also going to be a lot more careful as far as which sites I go to.
I wish I new more about this shit, but I am telling you what I know.
Good luck.