It's adware, actually.
I expect to be out of sorts for the next couple of days -- my computer's been infected with some of the nastiest adware I've ever seen, and I'll have to take some time out to try and fix it. If I can't do it on my own, I'll have to get to a technician and ask for a reformat and reinstallation. The outlook seems to be rather bleak; I spent nine hours trying to remove it yesterday afternoon and evening, with few visible results apart from a slow computer.
I've done my initial cursing already, and I'm firmly in resolution mode right now. I'll get back to my ranting and whining once I can get normal operations resolved over here.