Article ID: 981215 - View products that this article applies to.
Chat channels in Microsoft Office Communications Server 2007 R2 Group Chat client become unavailable.
This problem is caused by SQL deadlocks that occur on Office Communications Server 2007 R2.
To fix this problem, apply the following update:
(https://support.microsoft.com/kb/979857/ )Description of the update package for Office Communications Server 2007 R2: April, 2010
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Article ID: 981215 - Last Review: October 6, 2011 - Revision: 2.0