At the office here I use Fire Fox and it works relatively well for me, there are a few things I don't like the way FireFox handles... even in IE sometimes it is helpful to use the hard logout button (next to the date above where it says Log In/Out) that will kill the cookies for the site, which might help your problems. Although erasing the cookies from the other menu as described about should do the same.

We havent changed much here I suspect its just a firefox problem.

Tony