This is a copy of a story that I wrote for one of my other websites, FYI!
I have had a few run-ins with PayPopUps taking over my websites. I was going insane trying to lock down the cause to the point where I took ALL my widgets and gadgets off 3 of my sites just so my readers could actually get to the reading material without enduring the painful page sized PayPopUps. When I had my third go round with these I started to think outside the box. I knew that the templates were not the cause since I used 3-4 different ones per site without success. I knew there was something on these sites that was very wrong because my fourth site was pop-up free and had been clean since the beginning. I finally found the answer to my problem and was I 'pissed'!
All I can advise you to do before installing any widget or gadget to your website is to 1. who is the author of the widget, 2. what is it going to do, 3. does it have a relationship to the name on the widget, and 4. what are you agreeing to let it do to your site? I never checked 1-4 when I installed a Google Page Rank widget on my 3 sites. That's the one that I trusted to be a Google product and continuously returned to the sites. The 4th site didn't want widgets because it's a business site. I happened to be looking for a newer style of PR widget and went to where I found the last one when I couldn't find the widget on Google gadgets. Come to find out that the Google PR widget was a third party widget that, when you installed it for your rank to show, I agreed to allow a pop-up to take place when the page was opened and advertise a product or service of their choice. I was livid, not so much at them but at myself, for not reading further when I found the widget. I've found similar widgets on other sites that do the same thing this one did.
I have NO Google Page Rank widgets on any of my websites and have had no further incidents like these happen again. My advertisers were getting quite upset when they couldn't gain access to my site to see their adverts. The adverts help defray the costs of these sites but what do they care. Just beware when you grab that 'cool' widget or gadget. Read the whole page for conditions! Happy Motoring!