I have similar problems too Jake, although I don't run windows.
I do run a program called no script which allows me to determine if sites can run scripts or not. If i can access what i want on the AFL site without allowing scripts to run then I'm fine, but once I allow their their scripts to run Firefox freezes and I get a message about a script causing problems and do i want to wait or stop the script in question.
So it seems that at least one of the scripts on the AFL site doesn't agree with Mozilla