Media Player 9 problem

For some reason I can't Paly Movie files unless I grab the window and move it back and forth? The movie will play for a second or two and then the action on the screen just stops but the file and sound continue to play, however if I grab the window and move it back and forth the movie will play as normal, but a bit slow. any ideas? I had Media Player 7 and upgraded to 9 to see if it would fix it but it didn't. Any help is most appreacited. Thanks.

http://support.microsoft.com/default...b;EN-US;811981
MP9 + NT4 = unstable MP.
MediaPlayer 6.4 was last release supported by Windows NT.
MP7 has been known to work but was not supported by M$.