Windows Media Player 9 error message

Hi,

I'm trying to play an avi clip on Windows Media Player 9,
but I keep getting an error message when I try to open
the file : "An operation failed due to a certification
failure". Other avi clips have played with no problems
whatsoever. The clip that's giving me the error message
used to play well too, but I just re-installed my Windows
XP Pro, got all the new updates from Windows Update, and
that clip doesn't open.....does anyone know what that
error message means?

Thanks a lot,

Jose