I dunno. The pop-up problem was only happening on LJ, and friends of mine have reported the same thing here but nowhere else.

I use Firefox at home and IE at the office and it works the same in both places. My virus scans at home have been clean for ages.

NOTE: my friends were reporting the pop-ups long before I could see them, but eventually they started showing up for me too -- maybe your turn is still to come! :D