Hi,
I don't have much more ideas...
In your initial post, there is this warn message:
18:03:57,957 WARN [arjLoggerI18N] [com.arjuna.ats.arjuna.coordinator.TransactionReaper_18] - TransactionReaper::check timeout for TX a0000ee:cd57:4ee7bc75:63 in state RUN
This might be related to JMS configuration: http://community.jboss.org/thread/148206 - do you use a message driven bean or JMS queues?
In your second post, there are two other error messages. They both can be ignored, they are "known" warn messages. See here: http://community.jboss.org/message/251030
One common cause of trouble is a JAR conflict. So, could you post a list of all JAR files bundled with your app?
Best regards
Wolfgang