harvester running for a long time looses JMS connection

It seems that if a jobs has been running for a long time (days) it looses the JMS connection - so that

• it cannot upload any files
• it cannot report back about the finish of the job (so the job remains in status STARTED)
  Could be a problem with autocreated JMS-queues getting destroyed automatically?:
  http://docs.sun.com/app/docs/doc/819-7759/6n9mco7hh?a=view
  Or the client looses the connection when it has not been used for a long time?
  The harvester goes:
  kb-prod-har-002.kb.dk
  dk.netarkivet.harvester.harvesting.distribute.HarvestControllerServer$HarvesterThread.run(HarvestControllerServer.java:626)
  Fatal error while operating job 'Job 21429 for HD: 53'
  dk.netarkivet.common.exceptions.IOFailure: Send failed.
  at dk.netarkivet.common.distribute.JMSConnection.sendMessage(JMSConnection.java:308)
  at dk.netarkivet.common.distribute.JMSConnection.send(JMSConnection.java:241)
  at dk.netarkivet.harvester.harvesting.distribute.HarvestControllerServer.processHarvestInfoFile(HarvestControllerServer.java:549)
  at dk.netarkivet.harvester.harvesting.distribute.HarvestControllerServer.access$300(HarvestControllerServer.java:82)
  at dk.netarkivet.harvester.harvesting.distribute.HarvestControllerServer$HarvesterThread.run(HarvestControllerServer.java:621)
  Caused by: javax.jms.IllegalStateException: [C4059]: Cannot perform operation session is closed.
  at com.sun.messaging.jmq.jmsclient.SessionImpl.checkSessionState(SessionImpl.java:1756)
  at com.sun.messaging.jmq.jmsclient.SessionImpl.createObjectMessage(SessionImpl.java:1849)
  at dk.netarkivet.common.distribute.JMSConnection.sendToQueue(JMSConnection.java:360)
  at dk.netarkivet.common.distribute.JMSConnection.sendMessage(JMSConnection.java:304)
  ... 4 more