Are you using jbm (version) or jboss mq? Is you mdb colocated with your messaging service (jbm/mq)? and is your messaging server clustered?
If your mdb sits ourside the messaging server and the network latency is not ignorable, you may want to set a reasonable large value of validatorPingTimeout.
I am using Jboss MQ and everything is on the same server and i am not in a cluster.
It has something to do with the data directory .
This is the JBoss Messaging forum, if you post on the JBoss MQ forum they will be able to help you