Recently, the Mavericks changed the function of power button from showing up a shutdown menu to going to sleep right away. Here is a quick way to kill your MBA. If you press the power button to make it go to sleep. Quickly press the power button (to wake it up) again. Highly likely you will see the keyboard light is on and the computer is hanged. I thought it's a machine failure and changed it to other MBA. But it happens again with the new machine. I guess it's because too much quick attempt to wake it up makes the OS hanged. Anyone has a different opinion?