DVD playback may stop when exiting full-screen mode in Windows Media Center for Windows Vista with the Windows TV Pack for Windows Vista Media Center
In Windows Media Center for Windows Vista with the Windows TV Pack installed, when playing a DVD in full-screen mode, if you exit full-screen then quickly return to it, DVD Playback may stop. Also, you may encounter a black screen.
This can also happen when playing a DVD in Windows Media Center with the Windows TV Pack installed under the following additional scenarios: if the screen resolution is changed, when extending the desktop to multiple displays, moving the Windows Media Center desktop between displays, and finally resuming from sleep or hibernation (S3 and S4 sleep states).
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB968214.