you may have spyware running on your computer ---there are hundreds of spyware programs out there ---here is a free one ---it is not the one I use I paid for one ---but it is better than not having one

Free Spyware Scanner identifies surreptitiously installed applications. Using updatable ref lists similar to antivirus DAT files, Free Spyware Scanner scours your system, including the registry and temporary Internet files, and looks for traces of recognized adware modules. When it's finished searching, it displays a list of what it found.

http://www.download.com/Free-Spyware...ml?tag=lst-0-2