Apple just released an update to all mid 2010 MBP that experienced the black screen / freeze issues on the built in display. I wrote an article on this in the past.
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.
In addition to the update, Apple has decided to extend the warranty for two years from the day of purchase for all the mid 2010 MBPs:
Apple will service affected 15-inch MacBook Pro computers free of charge until two years from date of purchase. Apple will provide further extensions to this program as needed. This worldwide Apple program does not extend the standard warranty coverage of the affected MacBook Pro.
Here is a link to the kb.
All you have to do is to run Software Update on your mac and there you will see the “MacBook Pro Video Update”. Just install it.
Let us know if this problem solved.