Clustered SSO's TreeCacheClusterManager is using MBeanServerLocator.locate() instead of locateJBoss() to find the MBeanServer. This results in locating the wrong MBeanServer if more than one exists in the VM; e.g if the -Dcom.sun.management.jmxremote switch is used. The problem manifests itself with a log message like the following when the tree cache mbean can't be found in the incorrect server:

ERROR [org.jboss.web.tomcat.tc5.sso.TreeCacheSSOClusterM
anager] Cannot find TreeCache using jboss.cache:service=TomcatClusteringCache –
TreeCache must be started before ClusteredSingleSignOn can handle requests

This was fixed in July on the 4.0 branch and HEAD; I'll port the fix to the 3.2 branch.