Unless you use another chat client that can join IRC chat rooms, you are using the Java-based client at http://huskerboard.com/chat. If that isn't working, make sure your Java environment is up to date.
You can do this by going to http://java.com and clicking the big FREE DOWNLOAD button. Let it install the latest Java environment and then restart your computer. After that, try to join the chat again.
We are trying to use the chat not only for game days, but for organized chats as well. Stay tuned!