When you use a custom application to keep track of the availability status of different Office Communicator users, the Response Group Service (RGS) that runs on Office Communications Server 2008 R2 stops responding. This occurs when the application interacts with the server. To clear the error, you must restart the server.
This problem occurs if the custom application sends the availability status information to the Response Group Service in XML, and the XML does not use the presence schema <availability> tag. When this occurs, the Response Group Service stops responding.
How to obtain the hotfix
This issue is fixed in the Office Communications Server 2007 R2, Response Group Service hotfix package update package. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
975612 Description of the cumulative update for Office Communications Server 2007 R2, Response Group Service: October 2009
To work around this problem, make sure that the XML that your custom application passes to the Response Group Service uses the presence schema <availability> tag. For more information about the Office Communications Server 2008 presence schema, visit the following MSDN Web site:
7 Appendix B: Full text/xml+msrtc.pidf Presence Document Format
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.