Upgrading seemed to get rid of them for a bit but now we've cleared some other problems they've come back. I'm a bit confused now though. We changed one of our entity beans to READ_ONLY and JBC complained that it couldn't get a write lock on it, even though it's only ever pulled from the DB and never modified. The problem went away when we changed the isolation level, which I thought as we were using OPTIMISTIC locking should always be ignored. From what we can see the system is taking a write lock all the way up the tree from the target node to the root node whenever it wants to modify anything. Whereas we obviously only want it to take a lock on the node to be modified. So.... 1. We want the system to only take a write lock on the nodes it's actually changing. What should we set? 2. All transactions with our entity beans are managed by the JBoss transaction manager. If we change the isolation level to NONE will the transaction manager look after the integrity of the data for us? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4146530#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...