Consider the following scenario:
You use Outlook 2010 to log on to a Microsoft Exchange Server 2010 mailbox.
You add a Public Folder Calendar Folder to the Public Folders Favorites list, and then you log off.
You use Outlook Web App (OWA) to log on to the mailbox.
You view the Calendar view, and then log off.
You use Outlook 2010 to log on to the mailbox again.
In this scenario, the Public Folder Calendar folder is missing in the Public Folders Favorites list of the mailbox.
This issue occurs because the Public Folder Calendar folder in the Favorite list cannot be recognized correctly when the OWA Calendar module is loaded. Therefore, the folder is incorrectly added to the InvalidNodeList list, and then the folder is removed.
To resolve this issue, install the following update rollup:
2645995 Description of Update Rollup 1 for Exchange Server 2010 Service Pack 2
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
2417084 A public folder disappears from the Public Folder Favorites list of an Exchange Server 2010 mailbox