An external monitor does not turn on after you reconnect it to a Windows Vista-based portable computer after the monitor is disabled and re-enabled
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.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB959657.