For a couple weeks ive been getting seemingly random popup/under ads for things after clicking a link. Not always, or even most of the time, but enough for me to notice. I can't seem to make it stop. I have Firefox's popup blocker enabled, Ive tried doing a clean refresh. Ive scanned my computer with malwarebytes, ad-aware. microsoft security essentials, and Nod32. None of them found a single problem.

But the popup ads keep coming! What should I do to stop them?