Sounds like a virus or worm, We are on to this one
Check your system using any of these programs (I reckon using all of them):
This one first it has the fix you need, Update before scanning.
http://www.grisoft.com(good free AVG)
Select Your Product - Home - Lavasoft)
http://www.ewido.com(>>now called AVG Anti Spyware<< free 30 day trial -the best in my opinion)
http://www.ccleaner.com/download/(free)
Spybot - Search & Destroy (FREE)
You can also read here point 4 in the post of LOTR....:
http://www.gnutellaforums.com/showthread.php?t=41432