I have an Exchange 2003 organisation working in mixed mode with an Exchange 2003 cluster and two legacy Exchange 5.5 servers in the same mixed mode organisation.
The Exchange 2003 servers are v6.5 (Build 7638.2: SP2).
The Exchange 5.5 servers are v5.5 (2653.23: SP4).
When I attempt to creat a new Public Folder Store and I try to select the "Associated Public Folder Tree" I am only able to see one item in the Tree. However when I browse to 'Folders' in Exchange System Manager I am able to see two items in the tree. Suffice to say that the item that I want to set as the "Associated Public Folder Tree" is the item that is missing.