Running Exchange 2007 and Outlook 2007 on Windows XP clients.
Three users in my organization receive this error message when trying to open appointments on another user's calendar:
Cannot open this item. Cannot open the free/busy information. Cannot locate the recurrence information for this appointment.
I checked the latter's permissions on his calendar and he has delegated the following permissions:
User 1 - Reviewer; Read - Full Details
User 2 - Editor; Read - Full Details
User 3 - Reviewer; Read - Full Details
If the "Read" permission setting controls access to Free/Busy information, then I don't see why all three users can't view calendar items.