XAER_RMERR warnings and rollback exceptions

I'm using linux w/ Postgres 7.1.2 and the jdbc7.0-1.2.jar driver.

I'm getting the following waring from some sql updates which seem to be not ejb problems, but JDBC transaction problems is my guess.

What is this about XAER_RMERR meaning ... a resource manager error has occurred in the transaction branch? This msg occurs after a successful jdbc update into the dbase. In the 2nd case below this, the updates fail.

---
[WARN,TxCapsule] XAException: tx=XidImpl [FormatId=257, GlobalId=cassia//42, BranchQual=] errorCode=XAER_RMERR
javax.transaction.xa.XAException
at org.jboss.mq.SpyXAResource.commit(SpyXAResource.java:102)
at org.jboss.tm.TxCapsule.commitResources(TxCapsule.java:1490)
at org.jboss.tm.TxCapsule.commit(TxCapsule.java:324)
at org.jboss.tm.TransactionImpl.commit(TransactionImpl.java:76)
at org.jboss.jms.asf.StdServerSession.onMessage(StdServerSession.java:314)
at org.jboss.mq.SpyMessageConsumer.sessionConsumerProcessMessage(SpyMessageConsumer.java:565)
at org.jboss.mq.SpyMessageConsumer.addMessage(SpyMessageConsumer.java:376)
at org.jboss.mq.SpySession.run(SpySession.java:248)
at org.jboss.jms.asf.StdServerSession.run(StdServerSession.java:172)
at EDU.oswego.cs.dl.util.concurrent.PooledExecutor$Worker.run(PooledExecutor.java:725)
at java.lang.Thread.run(Thread.java:484)

--- at a later point in a completely different sql call, I get this following the warning ...

[ERROR,StdServerSession] failed to commit/rollback
javax.transaction.RollbackException: Unable to commit, tx=XidImpl [FormatId=257, GlobalId=cassia//80, BranchQual=] status=STATUS_ROLLEDBACK
at org.jboss.tm.TxCapsule.commit(TxCapsule.java:351)
at org.jboss.tm.TransactionImpl.commit(TransactionImpl.java:76)
at org.jboss.jms.asf.StdServerSession.onMessage(StdServerSession.java:314)
at org.jboss.mq.SpyMessageConsumer.sessionConsumerProcessMessage(SpyMessageConsumer.java:565)
at org.jboss.mq.SpyMessageConsumer.addMessage(SpyMessageConsumer.java:376)
at org.jboss.mq.SpySession.run(SpySession.java:248)
at org.jboss.jms.asf.StdServerSession.run(StdServerSession.java:172)
at EDU.oswego.cs.dl.util.concurrent.PooledExecutor$Worker.run(PooledExecutor.java:728)
at java.lang.Thread.run(Thread.java:484)

Any help much appreciated.