Currently in our environment we are experiencing the issue detailed here: http://support.microsoft.com/kb/2849083
I've confirmed that the exact property is being corrupted: "PR_Sent_Representing_Name" . We have had Exchange 2010 SP2 Rollup 6 installed for quite a while now, but recently we have had a big uptick of reports on this issue. The KB doesn't really mention how this happens, or if it is caused by an specific actions. All of the reports we have had come from admin assistants trying to update other calendars they manage. We have also noticed that this is not necessarily limited to meetings where the calendar owner is the organizer. All affected users are on Outlook 2010, so far we haven't seen any reports of users on Outlook 2007.
From everything I have read there is not yet a patch for this issue. Has anyone been able to find any root causes of this issue? Or seen an uptick in occurences lately?