Consider the following scenario:
You join an online meeting or a group conversation by using Microsoft Lync 2010.
Note You and user A are both presenters.
User A presents one slide of a PowerPoint presentation.
You move away from the presented slide.
You accidentally double-click the Return to Presenter’s View button.
In this scenario, you take over the presentation unexpectedly.
This issue occurs because the second click clicks the Take Over as Presenter button.
To resolve this issue, install the following cumulative update:
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.