Article ID: 978719
You use some USB audio devices to make calls in Microsoft Office Communicator 2007 R2. When you mute the microphone, CPU usage may increase significantly.
To fix this problem, apply the following update:
(https://support.microsoft.com/kb/976135/ )Description of the Communicator 2007 R2 cumulative update: January 2010
Article ID: 978719 - Last Review: June 21, 2014 - Revision: 2.0