MacBook Pro (15-inch, Mid 2010): Intermittent black screen or loss of video
Symptoms
Apple has determined that a small number of MacBook Pro (15-inch, Mid 2010) computers may intermittently freeze or stop displaying video on the built-in display or on an external display connected to the MacBook Pro. In this situation, you may also see a restart warning message before the video is lost or the display turns black or gray. Affected computers were manufactured between April 2010 and February 2011.
Products Affected
MacBook Pro (15-inch, Mid 2010)
Resolution
For computers with OS X Lion, v10.7
Run Software Update from the Apple (?) menu to update your computer to version 10.7.2, then install MacBook Pro Video Update 1.0. If the symptoms persist after installing the update, select one of the service options below.