Article ID: 2448009 - View products that this article applies to.
Consider the following scenario:
This issue occurs because Lync 2010 uses a different events order from Office Communicator 2007 R2. In Office Communicator 2007 R2, when a sharing switch happens, the passive viewer obtains a notification about the new sharing session, and then discovers that the old sharing session has stopped. Therefore, the passive viewer stays in the application sharing session. However, the events come in reverse in Lync 2010. Therefore, when Office Communicator 2007 R2 users interoperates with Lync 2010 users, this issue occurs.
To resolve this problem, install the following update rollup:
(http://support.microsoft.com/kb/2291453/ )Description of the cumulative update package for Communicator 2007 R2: November 2010
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.