Dean,
>I have setup hostnames for all transports in the hostnames panel <
You do not need to do this as explained on the Hostname configuration page this is done automatically for you. When you enter your hostname xxxx.com, aim.xxxx.com, jud.xxxx.com, conference.xxxx.com etc are automatically set. If you want something different then the XML files need to be manually changed.
Now, if the last hostname you entered was jud.xxxx.com jabber will try to resolve jud.jud.xxxx.com or msn.jud.xxxx.com. This wont work and is probably why you are having problems.
You need to go back and just set the hostname to your hostname, nothing else, then restart the server.
Jon
p.s just noticed that on the host configuration page conf.your_domain is supposed to be conference.your_domain.