wm player 9 restarts my comp

[mAtt]

hi

I have just been noticing recently that whenever I play
particularly large mpeg files on windows media player 9
series, it gets to about a quarter of the way through
playing the file, then my computer just restarts, for no
apparant reason!

This has never happened before, and yes, I have tried
playing these large mpeg files on other players, and they
too freeze, then after a few seconds, my computer
restarts.

any help is appreciated...:)
mAtt