Hi,
I encountered a very similar problem to what you are seeing a few weeks ago and it did take a bit to track down.
There are various specific configuration options for your broker that you can lock down in your domains/<your domain>/imq/instances/imqbroker/props/config.properties file.
For instance the jms.tcp.port kept changing on me randomly so at the end of this file I added the property imq.jms.tcp.port=38669. After a restart it locked this service/protocal to port 38669.
If you are encountering problems with the rmiregistry used by jmx there is a configuration option for that port there as well.
Hope this helps.
S.D.
[Message sent by forum member 'samdoyle' (samdoyle)]
http://forums.java.net/jive/thread.jspa?messageID=231190