deadlock detected

  Explanation:  The system detected a set of processes waiting for
  locks  in  a  circular fashion (deadlock).  This lock request is
  denied in order to break the deadlock.

  User Action:  Recovery from a deadlock is application  specific.
  One common action is for the program to rollback the transaction
  and retry.  Deadlocks should be infrequent in properly  designed
  applications.