Well howdy Jen!
I just tried the chat room and got on with three different browsers - Internet Explorer, FireFox and Iron. All three worked in chat. I did see the black screen you mentioned, it popped up for a second before java kicked in.
I have had problems with chat in the past and they have cleared up before it got to the point of having to make an issue of it. They mysteriously came and went on their own. This isn't to make light of your problems, just to illustrate I have no idea of how it works or what's going on.
There was a fairly recent update to java - a few weeks ago - I remember seeing it downloading. There may also have been windows updates - any of this stuff can affect the house of cards. From what you describe, it sounds like Java is not loading for you. Just about anything I could suggest would be just a guess.
I guess a place to start is - what OS are you using? Windows? What flavor? (xp, 7, etc.)
What browser are you using? FireFox? Explorer?
When did you notice this problem? Was that the first time you had tried the chat in a while? or was it working the hour/day/week before when you used it last?
How willing are you to dig into the guts of your computer to try and resolve the problem? You could try downloading a fresh version of Java and installing that? Or try a different browser and see if that fixes the problem. Not saying you have to switch browsers, but if it fixes the problem that narrows it down to something hinky going on with your old browser..
Oliver (admin) has a bunch of these forums that he runs, so doesn't always get back right away. Posting here is a good place for general help from other users and mods, but if you are not getting response in a reasonable amount of time just PM me. When I get a PM it sends me an email. I'm not always handy to the computer, but when I see a PM email, I try to get back in a reasonable amount of time.