XI - Error when activating configuration

We did a "clean" install of PI 7.0 on Windows 2003 server / MSSQL and performed the post-installation config all as per instalation guide. All works fine, except when activating PI config from the Integration Directory. The activation works, but after a few seconds the following error comes up in the PI configuration:

Unexpected error during message processing: javax.transaction.HeuristicMixedException: com.sap.engine.services.ts.exceptions.BaseHeuristicMixedException: One or more XAResources were not commited because of Exception in the second commit phase. at com.sap.engine.services.ts.jta.impl.TransactionImpl.commit(TransactionImpl.java:451) at com.sap.engine.services.ts.jta.impl.TransactionManagerImpl.commit(TransactionManagerImpl.java:319) at com.sap.engine.services.ts.jta.impl.UserTransaction.commit(UserTransaction.java:79) at com.sap.aii.ib.server.notification.AbstractMessageReceiver.commitMsgProcessingTx(AbstractMessageReceiver.java:223) at com.sap.aii.ib.server.notification.AbstractMessageReceiver.onMessage(AbstractMessageReceiver.java:138) at com.sap.jms.client.session.Session.run(Session.java:641) at com.sap.engine.core.thread.impl3.ActionObject.run(ActionObject.java:37) at java.security.AccessController.doPrivileged(Native Method) at com.sap.engine.core.thread.impl3.SingleThread.execute(SingleThread.java:100) at com.sap.engine.core.thread.impl3.SingleThread.run(SingleThread.java:170) Caused by: javax.transaction.xa.XAException: XA operation cannot be completed successfully. at com.sap.jms.client.xa.XAResource.commit(XAResource.java:47) at com.sap.engine.services.jmsconnector.spi.ManagedSession$XAManagedResource.commit(ManagedSession.java:322) at com.sap.engine.services.ts.jta.impl.ResourceList.commitTwoPhase(ResourceList.java:80) at com.sap.engine.services.ts.jta.impl.TransactionImpl.commit(TransactionImpl.java:355) ... 9 more

Any ideas?

Thanks

Johan