This is recommended for all of the users of Mac OS X Lion 10.7 client and server to upgrade their Mac machines to the first update of OS X Lion v10.7.1 which includes general fixes to enhance the stability and compatibility of systems.
OS X Lion 10.7.1 Update Includes:
Address an issue that may cause the system to become unresponsive when playing a video in Safari.
Resolve an issue that may cause system audio to stop working when using HDMI or optical audio out.
Improve the reliability of Wi-Fi connections.
Resolve an issue that prevents transfer of your data, settings, and compatible applications [...]