A corrupt calendar item can reallly mess-up a custom application and even some very seasoned applications. If there is a corrupt item/items, then those should be cleared-up ASAP before trying to do some sort of code work-around. If you are suspecting calendar corruption, you should consider using one of the following.
CalCheck – The Outlook Calendar
Exchange 2010 has a feature called the Calendar Repair Assistant:
Understanding Calendar repair
Exchange 2010 Calendar Repair – Part 1
Exchange 2010 Calendar Repair – Part 2
Poof Your Calendar – Really!
Checking if a meeting has a duplicate UID with MFCMapi:
Its possible to have a duplicate UID accross meetings in a calendar, thats bad. UID’s in meetings need to be unique. The problem is that its up to the client or client’s API to generate a UID. Meeting updates sent by mail are matched using the UID, so if there is a duplicate Exchange may not pick the correct meeting to update.
One way to check for dupliate UIDs in a calendar is to use MFCMAPI to navigate to the calendar folder, drill down to the items, scroll to the right until you see the UID property and then sort the list. From there, you can scroll down until you see the UID of your meeting and check for entries above and below it to see if they have the same UID – if you do, then pick one for removal.