download spybot and run it
let it update and backup your registry, this may take a while depending on your machine speed.
than run the scanner... and see what it finds
remove anything it finds
yeah mixx is right, you should post a picture of what your seeing, it sounds to me like spyware or malware on your machine, i wouldnt worry about it, its just companies trying to get your attention to buy their software.
if you see the pop up again
press Print Screen button on your keyboard, go into microsoft paint
and press edit paste
save the file and send post it up here