Clustering Error: UnsupportedOperationException

When running the "all" configuration for clustering, I've noticed the following exceptions being thrown in server.log. I have two identical JBoss instances in the cluster (DefaultPartition) on two distinct hosts.

When a run a J2EE app. on one instance, the other instance which is replicating the other throws these exceptions in the log. The two servers will work "for a while" (about an hour under low load), before the second server gives-up altogether and starts serving out blank pages for all requests.

2005-01-07 22:57:09,419 ERROR [org.jgroups.blocks.RpcDispatcher] failed invoking
method
java.lang.UnsupportedOperationException: commit() should not be called on TreeCa
che directly
at org.jboss.cache.TreeCache.commit(TreeCache.java:2783)
at sun.reflect.GeneratedMethodAccessor154.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at org.jgroups.blocks.MethodCall.invoke(MethodCall.java:236)
at org.jboss.cache.interceptors.CallInterceptor.invoke(CallInterceptor.j
ava:37)
at org.jboss.cache.interceptors.Interceptor.invoke(Interceptor.java:40)
at org.jboss.cache.interceptors.LockInterceptor.invoke(LockInterceptor.j
ava:126)
at org.jboss.cache.interceptors.Interceptor.invoke(Interceptor.java:40)
at org.jboss.cache.interceptors.CreateIfNotExistsInterceptor.invoke(Crea
teIfNotExistsInterceptor.java:47)
at org.jboss.cache.interceptors.Interceptor.invoke(Interceptor.java:40)
at org.jboss.cache.interceptors.ReplicationInterceptor.replicate(Replica
tionInterceptor.java:210)
at org.jboss.cache.TreeCache._replicate(TreeCache.java:2733)
at sun.reflect.GeneratedMethodAccessor97.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at org.jgroups.blocks.MethodCall.invoke(MethodCall.java:236)
at org.jgroups.blocks.RpcDispatcher.handle(RpcDispatcher.java:220)
at org.jgroups.blocks.RequestCorrelator.handleRequest(RequestCorrelator.
java:615)
at org.jgroups.blocks.RequestCorrelator.receiveMessage(RequestCorrelator
.java:512)
at org.jgroups.blocks.RequestCorrelator.receive(RequestCorrelator.java:3
26)
at org.jgroups.blocks.MessageDispatcher$ProtocolAdapter.handleUp(Message
Dispatcher.java:722)
at org.jgroups.blocks.MessageDispatcher$ProtocolAdapter.access$300(Messa
geDispatcher.java:554)
at org.jgroups.blocks.MessageDispatcher$1.run(MessageDispatcher.java:691
)
at java.lang.Thread.run(Thread.java:534)