Why won't Firefox display pages?

sounds like virus/malware to me. run a virus scan, chances are there is some crappy popup malware, or site blocking thing going on.

also, press ctrl+alt+del and check the task manager, make sure the CPU is not running at 100% or some other crazy high number.

EDIT: if by any chance you have been looking up porn, or downloading pirated video games, or anything with the words “warez” in it, then the virus possibility is much higher. torrents, p2p programs like limewire, all risky stuff. (not judging, just commenting)

The mysteries of the internet.