Ok... my usual routine...
1. Download the program Spy Sweeper by Webroot. Install, update defs, run program. Can't remember home page but you can find it w/ google.com
2. After 1, Download Avast Anti-Virus at
www.avast.com , update and then run. If your think "I already have , I don't need another one" well, i've seen Avast pick up things that McAfee, Norton and various other Virus Scanners missed. You don't have to register for anything, and it gives you a 60 day free trial.
3. If you don't have any viruses, or Adware, you can try to clean out your registry yourself. I can help you out, but i suggest you do steps 1 and 2 before trying anything else.
4. Just Re-Install windows without a format.