I’ve had my 13-inch MacBook Air since they were first released and although I encountered video problems initially after the plethora of updates that Apple has released the video problems haven’t returned.
The updates included an EFI firmware update, a specific software update for the MacBook Air 2010 model, and the Mac OS X 10.6.5 software update. I even offered not one, but two suggested solutions to try.
These updates and suggested fixes worked for some, but unfortunately they didn’t work for everyone. People are still complaining on Apple Discussion Forums about problems they are encountering when connecting their MacBook Airs to external displays.