I am using hibernate 3.6.1 and jpa . At certain times when i try to commit the data into database i seem to get the following exception

Exception in thread "pool-2-thread-1" javax.persistence.RollbackException: Error while committing the transaction
at org.hibernate.ejb.TransactionImpl.commit(TransactionImpl.java:93)
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1214)
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1147)
at org.hibernate.ejb.TransactionImpl.commit(TransactionImpl.java:81)
... 5 more
Caused by: org.hibernate.exception.JDBCConnectionException: could not update
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:99)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:2612)
at org.hibernate.persister.entity.AbstractEntityPersister.updateOrInsert(AbstractEntityPersister.java:2494)
at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:2821)
at org.hibernate.action.EntityUpdateAction.execute(EntityUpdateAction.java:113)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:273)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:265)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:185)
at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321)
at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:51)
at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1216)
at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:383)
at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:133)
at org.hibernate.ejb.TransactionImpl.commit(TransactionImpl.java:76)
... 5 more
Caused by: java.sql.SQLRecoverableException: Closed Statement
at oracle.jdbc.driver.OracleClosedStatement.setObject(OracleClosedStatement.java:578)
at oracle.jdbc.driver.OraclePreparedStatementWrapper.setObject(OraclePreparedStatementWrapper.java:238)
at org.apache.commons.dbcp.DelegatingPreparedStatement.setObject(DelegatingPreparedStatement.java:163)
at org.apache.commons.dbcp.DelegatingPreparedStatement.setObject(DelegatingPreparedStatement.java:163)
at org.hibernate.type.EnumType.nullSafeSet(EnumType.java:147)
at org.hibernate.type.CustomType.nullSafeSet(CustomType.java:140)
at org.hibernate.persister.entity.AbstractEntityPersister.dehydrate(AbstractEntityPersister.java:2184)
at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:2558)
...

Kindly help me understand why i get this issue sometimes.

Thanks in advance,

James