‘have had a number of user complain that when they save an Out of Office Assistant (OOA) message, it is not sending out the new message but is sending out an old message. They check the message content in their OL2003 client and the new message saved. Somehow an old OOA message is used to reply to incoming messages.’
Had the same issue as this, found that in office 2003, rules and alerts under tools tab there was a rule setup forwarding an out of office reply to all incoming messages, deleted this rule. Out of office assistant then worked fine.