Why does my computer keep taking me to a page that says a href="http://ad.yieldmanager.com/imp%3Fz" rel="nofollow"http://ad.yieldmanager.com/imp…/a does not exist?

I'll just be looking at ebay or something and my computer will automatically take me to this page, like I searched it or something. I don't know alot about computers, so could you tell me how to solve this problem?