It sounds like you have picked up some sort of Malware along the way...
Try running a full system scan with your Aint-Virus protection and your Spyware apps...
If you don't detect anything and the problem still persists post your probem at one of these sites, these guys are experts at cleaning up your computer...
SpywareInfo Forum FAQ - SWI Forums
Bleeping Computer - Computer Help and Discussion
Here are some good free AV's and Spyware Apps (if you don't have any)...
Anti-virus:
avast!
AVG free
Avira Antivir
Antispyware etc:
Ad-Aware __(FREE)
Spybot - Search & Destroy __(FREE)
AVG Antispyware (formerly Ewido)
What to avoid when downloading files...
http://www.gnutellaforums.com/tips-t...wma-files.html
WARNING: Viruses on network you should be aware of!
How to add words to the filter
Keywords worth filtering