Outlook 2007 seems to have a bug that causes favorite folders to disappear frequently. I’ve been loosing my shared calenders often. We are still searching for a solid fix, but in the meantime here are the correct instructions to adding favorite folders back.
In outlook “Favorites” and “Favorite Folders” DO NOT mean the same thing.
To add a public folder to your “Favorite Folders” view in the “Mail” view in Outlook:
1. Navigate to the “Folder List” view in Outlook.
2. Navigate to any public folder, right click, then select “Add to Favorites”.
3. Still in the “Folder List” view, go to Public Folders >> Favorites >> [foldername].
4. Right click on the “Favorite” that you just created, select “Add to Favorite Folders”.
5. Your public folder will now appear in the “Favorite Folders” pane in the “Mail” view of Outlook.