I've been banging my head against a wall for the past day trying to figure out various FBJS problems in facebook. Turns out the problem was..... FireBug! By simply turning Firebug off, (most of) my problems went away. I have no idea what the issue is, but it took me forever to realize it because I always have FireBug on, and don't even realize it is there. It's never been a problem before. But, I noticed that one of my coworkers was using my app, with Firefox, with no problem, and I quickly realized that the problem was with FireBug.