The problem: Outlook won't open the calendars on another user's mailbox and and a room mailbox, even when users have permission.

Note: This problem is affecting more than one account on more than one machine.

So I have a room mailbox and a personal mailbox on Exchange, both with shared calendars. There is a security group called "Scheduling Users" that have editor rights on both of these calenders.

The room mailbox was created using PowerShell, per the instructions posted online (http://help.outlook.com/140/ee441202.aspx).

Sharing worked on both of these folders initially. Users can still access these folders using OWA.

So on to the problem. When users try to open these calendars in Outlook they receive one of the following messages.

• The set of folders cannot be opened. Microsoft Exchange is not available. Either there are network problems or the Exchange server is down for maintenance.

• Cannot open this item. Cannot open the free/busy information. The attempt to log on to Microsoft Exchange has failed.

What I have tried so far:

• Resetting the permissions on both of the mailboxes. I deleted the security group permissions on both mailboxes, applied the change, then waited a bit and gave the permissions back.

• Deleted the OST file of the shared calendar from the Outlook data directory

That is all I have been able to find online. Any thoughts? I have been going back and forth with the Office365 support folks for a while and they seem stumped too.