Edited by Joe AimonettiIf you have more than one MacBook or new MacBook Pro (models with a magnetic closing mechanism) you may experience an issue with the top computer going into sleep mode unexpectedly when stacked.
This issue is expected behavior and occurs because the magnet in the bottom computer could activate the magnetic switch in the top computer, causing the top computer to think that it has been shut. As Apple's KB Article on the subject notes:
"Automatic sleep operation works based on magnets; a switch in the MacBook Pro, known as a Hall Effect switch, is activated when the magnet in the display clamshell gets close to it. This is how your computer knows to go to sleep when you close the display."The solution, as the article mentions, is as simple as not stacking your notebooks. If you find yourself in a situation where you must stack them, try turning the bottom computer 180 degrees, so that the magnetic front of the notebook is facing away from the magnetic front of the top computer.