Outlook 2003 hangs for no apparent reason.

I recently installed Outlook 2003 (included with Office Professional 2003)
over my installation of Office XP and now, whenever I close Outlook 2003, it
hangs and refuses to shut down. I end up having to go to the Task Manager
Processes tab (it doesn't show as running in the Applications tab) to
terminate the process.

This happens every time I attempt to shut down Outlook 2003. I've tried
repairing the installation and reinstalling office and the service packs,
with no luck.

I'm running Windows XP on a P4 2.8gh processor with 512 mb of memory.

Any help would be appreciated as I'm ready to downgrade out of sheer
annoyance.