I've been having the same problem! I had installed a pop-up killer program, but it seems that after I took it off my computer, more pop-ups started appearing! Hubby says I should reformat my computer to get rid of them. It's so annoying.
There is another way to stop pop ups if you're using IE...go to "Tools" -> "Internet Options" -> "Security" Select "Custom Level" and scroll down towards the bottom of the list. You should see a category called Scripting...select DISABLE for "Active Scripting" and "Scripting of Java applets". This will stop pop ups from appearing...but it will also prevent you from getting on to some webpages (AngelFire, I think)...to switch it back to normal, just go back to the "Security" menu and click "Default Level". This will reset you to the default settings for the level you have selected.