You try to join an Audio/Video conference that is started by another Microsoft Lync 2010 user. The first attempt is unsuccessful because of insufficient bandwidth. In this situation, when you rejoin the conference, your audio and video is enabled automatically.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Article ID: 2464873 - Last Review: Jan 20, 2011 - Revision: 1
Microsoft Lync 2010