The Java chat can be very temperamental. Sometimes you can close out of the browser and try again, going slowly and waiting for any windows to pop up for you to accept security certificates.

Another alternative is to try theSlashNET Web Client, making sure to accept those certificates as well. Once logged in type /join #geocachingmaine to join the Maine chat.

The best way to use chat is to use a dedicated client. Chatzilla is a nice ad on for Firefox if you use that. Alternatively, there is mIRC and Trillian.

Using ChatZilla for Geocaching Maine chat

Setting up Geocaching Maine chat on mIRC

Setting up Geocaching Maine chat on Trillian