This sounds like some sort of network problem. In particular 2008-02-21 08:35:11,784 WARN [org.jgroups.protocols.pbcast.GMS] failed to collect all ACKs (3) for view [172.17.65.39:40883|5] [172.17.65.39:40883, 172.17.66.39:35267, 172.17.67.39:39896, 172.17.64.39:52927] after 5000ms, missing ACKs from [172.17.65.39:40883, 172.17.66.39:35267, 172.17.6 ..... sounds like 172.17.65.39:40883 is not able to get a response from itself to its own message. The OS should copy a multicast back to an in-machine listener making it go out on the wire, so not receiving your own message is a sign that either: 1) There's a problem with the network interface being used. 2) The thread that delivers messages has gotten stuck. Getting a stack trace can help show if that has occurred. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4191890#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...