Doc,
I am getting the same error and am just starting to research this
problem. In my case, an employee brought me a CD containing a Powerpoint
2003 file and five MPEG movie files. When I run the embedded movie files
from within Powerpoint (and from the CD), they run fine. Once I dragged the
MPEGs and Powerpoint file onto my harddrive (WINXP, SP2) and started up the
Powerpoint presentation, I can view an entire movie from within Powerpoint,
but at the end of the movie, Powerpoint bombs and displays the "MCI Error,
The specified device is now being closed". It is interesting that if I run
the MPEG movies from outside of Powerpoint, using Windows Media Player 10,
they run fine. This suggests that the problem is not with your video driver,
as Austin suggests, but something with the way Powerpoint and WMP interact.
Scargo