[otrs] Tickets not showing in queue

Hi guys, I'm running OTRS-1.3.2 on SLES 9 SP3. It started of as OTRS 1.0 or 1.1 (can't remember) and has been upgraded systematically since. however, the lat upgrade was just when 1.3.2 came out, and I haven't touched it since. Lately, in the last month or so, all tickets don't show up in the queue. The queue would show that there are say 50 tickets, but only 10 or so are displayed in the queue. This includes all the user queues. When you search for the ticket it does find it, and it is still open and functional. It just doesn't show in the queue. It also happens that tickets go "missing" and when you search you find that it is already closed. Any ideas why this is happening? Thanks Hans