Consider the following scenario:
- You connect an external monitor to a portable computer that is running Windows Vista.
- You disable the portable computer’s built-in display.
- The portable computer turns off the external monitor because of the lack of user activity.
- You disconnect the external monitor, and then you resume the portable computer.
- The portable computer’s built-in display turns on.
- You reconnect the external monitor.
In this scenario, the external monitor displays a black screen.