Unable to form a cluster Branch_5_x (flush by coordinator at xyz failed)

A cluster refuses to add more members. Problem detected on Friday 17th/4.

http://hudson.qa.jboss.com/hudson/job/as5-soak-ejb3-total-async-failover/64/console-perf01/
http://hudson.qa.jboss.com/hudson/job/as5-soak-ejb3-total-async-failover/64/console-perf02/
http://hudson.qa.jboss.com/hudson/job/as5-soak-ejb3-total-async-failover/64/console-perf03/
http://hudson.qa.jboss.com/hudson/job/as5-soak-ejb3-total-async-failover/64/console-perf04/

Coordinator fails to flush:
12:27:33,209 WARN [GMS] GMS flush by coordinator at 10.34.32.226:55576 failed

Joining node logs:
12:33:41,025 WARN [GMS] join(10.34.32.232:39410) sent to 10.34.32.226:55576 timed out (after 3000 ms), retrying

Command used to startup:
java -server -Xms256m -Xmx1024m -XX:MaxPermSize=256m -Dxb.builder.useUnorderedSequence=true -Dsun.rmi.dgc.client.gcInterval=3600000 -Dsun.rmi.dgc.server.gcInterval=3600000 -Djgroups.udp.ip_ttl=1 -Djava.net.preferIPv4Stack=true -Djboss.messaging.ServerPeerID=`hostname | cut -c "6"` -jar /tmp/jboss-5.1.0.CR1/bin/run.jar -c all -b `hostname` -Djboss.partition.name=SoakTestPartition -Dcluster.route.name=`hostname` -u 234.1.79.154