Sounds like Malware on your PC. Install, update, and run these programs in this order. They are all free for personal use, but some have limited functionality in the "free mode" - but those are features you really don't need to find and remove the problem that you have. '''(Not all programs detect the same Malware.)''' Malwarebytes' Anti-Malware - [http://www.malwarebytes.org/mbam.php] SuperAntispyware - [http://www.superantispyware.com/] AdAware - [http://www.lavasoftusa.com/software/adaware/] Spybot Search & Destroy - [http://www.safer-networking.org/en/index.html] If these don't find it or can't clear it, post in one of these forums for specialized malware removal help: [http://www.spywarewarrior.com/index.php] [http://forum.aumha.org/] [http://www.spywareinfoforum.com/] [http://bleepingcomputer.com]