A popup that DLed the program listed in the link above, and a couple of trojans, looks like.
AVG appears to have failed to remove one of the trojans (wavvsnet.exe) since it's showing up on a second scan.
I'm going to venture a guess and say you were using Firefox, and the "malware" popped up a bunch of windows that looked like system windows that didn't let you close them and kept saying your system was infected and that you should buy some kind of computer cleaning software.
I'm not using firefox, but basically correct.