On a computer that is running Windows Vista, the resources from the unused path may not get freed when the lid is closed or the laptop is undocked. So, when the lid is opened or the laptop is docked one or more monitors maybe blank.
Windows Vista may not try to call DxgkDdiCommitVidPn to destroy the unused path after the ACPI event triggered by the lid being closed or the laptop being undocked.
The recommended workaround for Vista is to have the provider of the video driver free the resources associated with the unused path after the lid-close or undock event rather than expect the path to always be removed by the operating system from the active VidPN.
Microsoft has identified this as an issue in Vista.