deadlock problem

I'm always getting deadlocks like this:

[30-Mar-2003 19:19:51] PHP Fatal error:  postgres7 error: [0: ERROR:
deadlock detected
] in EXECUTE("INSERT INTO users_foods (user_id, date, meal_id, quantity,
eaten, food_id) VALUES ('55283', '2003-04-07', '1', '1.00', 'f', '779')")in
/usr/local/www/generic/lib/adodb/adodb-errorhandler.inc.phpon line 71
 


Why would an INSERT cause a deadlock problem?  Is this due to the FOR UPDATE
problem with foreign keys?

Chris