Ok, so this is really weird:

I downgraded Firefox and updated it again, this time it loaded fine. The
only problem is that for some reason, it can't find realplayer. Every time
I go to a page that has embedded ralplayer or open a rm file in firefox, it
gives me a error message concerning realplayer. I haven't changed
realplayer and when I downgraded Firefox to 1.0.1, realplayer worked fine!
The _really_ bizarre thing is that when I reboot the machine, Firefox
becomes unresponsive as described in the message above. That's really weird!

Any ideas are most welcome.