Consider the following scenario:
You set the power setting when closing the lid on your laptop running Windows 8.1 to "Do nothing"
You set the power plan settings for turning off the display and putting the computer to sleep to "Never"
You connect the laptop to an external monitor via HDMI or DisplayPort, and output the display to the external monitor
You lock the PC and close the lid
While the lid is closed, you unplug the external monitor cable
After some time has passed, when you re-open the lid, you receive an error message:
Your computer is low on memory
The memory allocation will be reset once the external display is reconnected or if the system is rebooted.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.