Not sure about that, since tonight you said, if you close your browser and enter again to WP those popups appear again right? What about another site, they don't appear when you are on another site?
I guess it might be spyware, I can't say for sure, as I use FF I don't get popups in case there are, you might want to clean all the cache on your browser to see if that works, if not then use antispyware software like Spybot.
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?Everything is perfect in the universe - even your desire to improve it.?