Assume that you try to copy a folder to its subfolder by using Microsoft Office Outlook in online mode in a Microsoft Exchange Server 2010 Service Pack 1 (SP1) environment. In this situation, the Outlook client stops responding. Additionally, the Exchange Server 2010 SP1 server uses excessive CPU resources. Therefore, users cannot access their mailboxes that are located on the server.Note
This issue does not occur when you use Outlook in cache mode. However, if you use Outlook in cache mode, you receive the following error message:
A folder cannot be moved into one of its subfolders.