I too have the same problem. I went back to an older version of firefox in order to get my pogo games to work. I would imagine that any site using the java applets will not work with firefox. There is something in the new update that causes the applet to crash or break when started in the newest full version of firefox. I hope they get this bug fixed soon, I like to keep my software as up to date as possible.

with latest firefox version 3.6.14 every website (which loads java applets ), I have tried so far, crashes after page reloading as mentioned here https://bugzilla.mozilla.org/process_bug.cgi

sorry I mean here https://bugzilla.mozilla.org/show_bug.cgi?id=629030