I think they may have the same problem I have at home on my Mac (Except I use Safari)
If not, i'll explain what happens to me when I try to load the chat;
The window opens up and when it goes to load the Javascript for the chat, it just fails. I get a little 'X' in the top left hand corner of the screen and it offers me a choice to de-bug or something, which I have no clue how to do.
To both of you, go to java.com and make sure you have the latest Java, (Mac user, it should be in the Software Update menu on your Mac) and that should fix the problem.
(This is of course if you have the same problem as I do)
Cheers.