(1.4.1.SP9 stack trace)
Caused by: java.lang.NullPointerException
at org.jboss.cache.TreeCache.inactivateRegion(TreeCache.java:2363)

inactivateRegion uses marshaller_ without checking to see whether it is null.

marshaller_ is set as a side effect during initialization, but not if the cache is in LOCAL mode.
The other places it's used (registerClassLoader, unregisterClassLoader), it is initialized first if needed.