The OS X 10.9.2 update has broken AirPlay for many users of older model Macs. Symptoms range from AirPlay options being grayed out or missing, mirroring problems, low frame rate, lack of audio or video, sporadic mouse freezing, and random disconnects.

This is not affecting all Macs, and has been reported mostly with 2007-2011 models. Many have tracked down the problem to the installation of third-party applications like AirParrot or Air Display, and uninstalling them has corrected the issue. Others have found third-party apps are not the cause. See this Apple Discussion thread for more information: https://discussions.apple.com/thread/5939170