The Apple DVD Player application opens before the Multiple Users login screen appears.
Products Affected:
This issue happens when Multiple Users is turned on, and a DVD-Video disc is in the DVD-ROM drive when the computer starts up.
Solution:
Remove the DVD-Video disc from the DVD-ROM drive before shutting down or restarting the computer.
or
Open the Extensions Manager control panel and turn off the DVD AutoLauncher extension. To play a DVD video, open Apple DVD Player (in the Apple menu).