Connecting external display turns both screens black I updated from 10.8.1 to 10.8.2 for my MacBook Pro Retina with my external 27" Thunderbolt display. When I connect to my Thunderbolt display both screens are black. I can only see my mouse pointer and sometimes little boxes of display. Any idea what's wrong?
The solution explained in this Apple Discussions thread worked for me.


Delete /Library/Preferences/com.apple.windowserver.plist.
Delete ~/Library/Preferences/ByHost/com.apple.windowserver.XXXXX.plist.
Reset NVRAM.