Consider the following scenario:

• You connect an external display to a Windows Vista-based computer.
• You select the Show my desktop on my external display only option.
• You open the system display settings. Display 2 (the external display) is dimmed.
• You right-click 2, click Attached, and then click OK to enable the internal display and to set it to 2.

In this scenario, the internal display does not function.