The following event is logged on a Microsoft Office Communications Server 2007 R2, Group Chat server:
Log Name: Office Communications Server Source: OCS MGC Date: <Date> Event ID: 5377 Task Category: (1099) Level: Error Keywords: Classic User: N/A Computer: <Computer Name> Description: Failed to update the database with AD changes.  Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.
This issue occurs because an INSERT query in a stored procedure is not handled correctly.
To resolve this issue, install the following cumulative update:
2491973 Update package for Office Communications Server 2007 R2 Group Chat server: March, 2011
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.