Cant add new appointments to calendar

[Ken]

The calendar folder wiil not allow me to save new
appointments. When I go to save I get "message
interface has returned an unknown error...." Restarting
outlook does not fix the problem. I have all the current
office updates (SP3). The problem started when I
exported/imported a my .pst file between laptops via an
Iomega drive. Anyone know the fix?

If I can't fix it what file do I delete to start with a
whole new outlook and start from scratch. I uninstalled
and reinstalled office 2000 and my personal folder info
showed up on startup of outlook.

Thanks,
Ken