outlook 2k calendar resource disappears

We have our conference rooms set up as a non delegate mailbox resource in outlook 2000, exchange 2000. We can schedule these resources and everything shows up fine on the mailbox of the person who scheduled the resource, and on the resource calendar until the date of the appointment passes. Then the appointment diasappears from the resource calendar. Any ideas? If I schedule something directly on the resource calendar it is still visible past the date of the appointment.