What happens (in this instance) is that using Firefox the chat doesn't load at all, just displaying the message entering box, the tick icon, and "Default room: main". But it works fine using Chrome.
In Firefox the dd=1 version thing doesn't even show the "Default room: main", by the way.
Ah, I know what's causing that. If you are using Firefox, you have a really old version, just so you know.
Anyway, I was using a modern web technology thing, which isn't supported in old browsers and IE, and I've just added a library that implements it, so could you check if it works now.
... You should really update your system when you can. If only for the security things... It isn't like Skype where newer versions are universally crap.
It's fine for me in FF, too. Are you on the newest version, do you have any plugins that might affect the display, is it plugged in, have you tried turning it off and on again?