I had problems with the java chat application too so now use xchat (free trial at xchat.org then a token one-off payment around £15).
Others use similar IRC clients, such as icechat or chatzilla. The latter is a firefox add-in.
You'll need the following that I copied from the chat link page:
Some clients seem to use the terminology a bit differently but once you get it to work you can setup an automatic login for future sessions.