Microsoft Communicator for Mac 2011 13.1.2 Update

This update fixes critical issues in Communicator 2011, including issues that might cause Communicator to stop responding or quit unexpectedly. This update resolves an issue that causes Microsoft Communicator for Mac 2011 running on Mac OS 10.7 (Lion) to crash when you send an IM or start an audio call or a visual call. See https://support.microsoft.com/kb/2587147 for more information.

Get it @ https://www.microsoft.com/download/en/details.aspx?id=26835.