Outlook 2000 re-downloads same messages

Running outlook 2000 on most of my client machines. Running IP Switches IMail server, both POP and IMAP. Have a user who’s outlook is configured to leave a copy of their messages on the server until they delete it. The problem with this is that the user never empties their trash, thus the message never gets deleted. After enough times goes by, outlook re-downloads all the messages that are still on the server. How can I stop this.

Please only answer if you actually know of a solution. I am not one to give out points for poor attempts at guessing. If you need more info, just ask for it.