I have more or less posted about this already, but not hibernate specific (I was not sure about the cause, and am still not). From what I saw and read, I guess it is related to EJB3.0-SFSB, JBoss-Cache(1.4) and hibernate interaction. I have set up a Cluster of two JBoss 4.0.4.GA (modification: server uses host name rather than IP) with JBossCache 1.4.0GA. I have two similar EJB3 Beans one SLSB and one SFSB (the diff is just that one is SF the other SL). When I invoke multiple times on the SLSB all is fine (the invokation gets Loadbalanced via RoundRobin on bothe maschines). When I do the same with the SF Bean then I get a | 17:28:11,984 WARN [SessionFactoryObjectFactory] Not found: 2c9096b20c91acb4010c | 91ae85a50002 | This can happen on node one or two, depending where the first call has gone. So this happens when the SFSB allready exists. This then causes a failover to the node where the bean was created. I'm glad for any hints and tipps! Thanks ahead ! Marc I'll gladly post details again, since the other threads are rather verbose, but first of still just want to reference those here: JBoss.com -> JBoss User -> JBossCache http://www.jboss.com/index.html?module=bb&op=viewtopic&t=83655 JBoss.com -> JBoss User -> Clustering/JBoss http://www.jboss.com/index.html?module=bb&op=viewtopic&t=84650 View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3960284#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...