I get this error when I receive a calendar email

This meeting is not in calender: it may have been moved or deleted

When I doubleclick on a calendar that is already in my calendar, I get this
message
The operation failed

This is on fully patched Office 2003 with Outlook 2003, and fully patched
XPSP2, I uninstalled Outlook 2003 and reinstall Outlook 2003, but it did not
help. Cached Exchange Mode is enabled

Roaming profile enabled.