Article ID: 981448
When you make some changes in Microsoft Office Communications Server 2007 R2 Group Chat Server, it takes a long time to process the changes.
For example, you add many users to a Microsoft Office Communications Server 2007 R2 Group Chat Server. However, the Active Directory process changes takes a long time.
Processing the differences in channels is managed by Active Directory groups with a very large membership. Therefore, the change in the Active Directory process takes a long time.
To fix this problem, install the following update:
(http://support.microsoft.com/kb/980042/ )Update package for Office Communications Server 2007 R2 Group Chat Server: April 2010
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.