After I had my MBA for an hour I called AppleCare when I was confused about how to wake up the internal screen when I opened the lid (clamshell mode), while it was plugged into the external monitor (Apple Cinema Display 27 "). After resetting PRAM and SMC, it was not better. By pure luck, I pressed cmd + F2, which woke up the internal screen (still plugged into the external screen). I went in to a Apple Reseller where a staff linked up a MBP in an ACD in which the same sequence of events occured, the cmd + F2 was needed to wake up the internal screen after it has been in clamshell-mode. So I decided to live with it. One can also see it as a bug that has created a feature; I can open the lid so that the computer and the screen does not become hot and overheated. A few days later AppleCare called me, which considers the device to be replaced. I'm not sure what to think and do. I have done an extended hardware test without any errors. A bonus puzzle is that I can not change the lidwake setting (read more: man pmset), to set the display to wake up only by pressing a tangent or only by lifting the lid (without being connected to an external monitor). AppleCare does not support this because its a preference that could only be changed in the terminal. Its an expected behavior that the internal screen wakes up automatically when the lid is lifted. How does it work for you, is it just the same as for my MBA and the MBP which were tested in a store? And about the lidwake, is it a preference that you would never care about if it failed to change despite the fact that its a preference currently in use (according to pmset -g in terminal)?