DVD playback may stop when you exit full-screen mode and then quickly return to full-screen mode in Windows Media Center for Windows Vista
In Windows Media Center for Windows Vista, you play a DVD in full-screen mode. If you exit full-screen mode and then quickly return to full-screen mode, DVD playback may stop. Also, you may encounter a black screen.
When this problem occurs, you can recover only by clicking the green button in the upper-left corner of the screen to return to the main menu of Windows Media Center. However, when you play the DVD again, playback restarts from the beginning instead of from the location where it stopped.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB957574.