The operating system may stop responding when a Windows Vista-based or a Windows Server 2008-based computer that has multiple video cards resumes from sleep
You are using a Windows Vista-based or Windows Server 2008-based computer has multiple video cards installed. When the computer resumes from sleep (S3), the operating system may stop responding.
Note: If you are running an application that uses the DirectX kernel driver, a black screen may appear.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB967646.