I've got a few room resource calendars set up on exchange 2007. I log in to the calendar and give a particular security group "author" permissions to the calendar. But when people that are in that security group try to view items on the shared calendar they get free/busy errors. They can doubleclick items to open them once or twice before they get:
"Cannot open this item. Cannot open the free/busy information. You do not have sufficient permission to perform this operation on this object. See the folder contact or your system administrator."
Before they get that message, they can click on empty time slots and the schedule window will open. After they get that message trying to doubleclick an empty time slot gives a bubble with the same message.
If individual people are added rather than the group, it works fine - but I'd really like to avoid that. Also it seems like the problem doesn't affect all the calendars.
If I grant the security group "full mailbox rights" in ADUC, it also solves the problem. But that's another thing I'd like to avoid.
This also prevents printing the calendars (same error message).