As far as I know its a bug in jboss-remoting.jar
4.0.4GA and 4.0.5GA ship with version 1.4.3 of jboss remoting and this issue http://jira.jboss.com/jira/browse/JBREM-450 has the fix attributed to version 2 of jboss remoting.
As a result I have done the fix described in the forum thread (http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3942339#3942339) associated with this issue and recompiled jboss-remoting 1.4.3. As a result, both 4.0.4GA and 4.0.5GA now work if I use the modified jboss-remoting.jar
If you can't be bothered recompiling it I can email you the jar file.