deadlock detection

      We are currenlty using postgresql 7.2.1  database. But it does not seem to detect deadlocks .
       Suppose if a record is locked with update  command   and another concurrent user  tries to lock the same record and the first transaction for some reason , eg. m/c hangings   is not committed  both the transactions remains locked for indefinite period . I have checked the setting in postgresql.config  for deadlock_timeout  which is set to 1000 . Than why doesn't  the transaction deatect deadlock after 1000 millisecond  .
 Secondly if the frontend process  is killed but due to some reason the backend postgres process remains , than how can it be terminated .For
 if i try to use kill command all the postgres processes  gets terminated .
Please help

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Regards,
Shobha