Cannot read one instance of the recurring appointment
 

We recently upgraded from Exchange 5.5 to 2003. Some users have recurring
calender appointments pulled across with the upgrade. When you click one some
of them the following error occures 'Cannot read one instance of the
recurring appointment, Close any appointments and try again, or recreate the
appointment'. The application freezes and you have to crash out. Have tried
options discussed on other sites such as deleting FRMCACHE.DAT and use of
cahed exchange mode, but no joy. Interestingly if the calender is exported as
a .pst file and opened then the faulty recurring appointment does not appear.
This is also the case when accessing the calender from Outlook Web Access. If
I could just delete the appointment that would be good enough. Any help
appreciated.