use a pop up blocker, sometimes theres settings on internet explorer that allow you to block pop ups, however im not too sure on the instructions of how to do so, play around and try find it
Switch to mozilla firefox, download, then go to their page and get the noscript or adblocker. Not only is it alot more powerful, but it works trust me I used to have that problem with Internet Explorer too.
Also, it might be because you have adware or viruses on your computer I advise an immediate download of SuperAntiVirus and clean up your whole computer with a full scale scan. (Make sure to update the software regularly and it's free).