Article ID: 2517736 - View products that this article applies to.
Consider the following scenario:
This issue occurs because the second click clicks the Take Over as Presenter button.
To resolve this issue, install the following cumulative update:
(http://support.microsoft.com/kb/2496325/ )Description of the cumulative update package for Lync 2010: April 2011
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.