Windows Media 11 No picture?

I have found that when I try to run a video on Windows Media 11, I see no
picture (on my external screen). All I seem to see is a very dark box on a
black background. I can hear the sound, but get no pictures. Even items in
the Library do not appear.

I am running Windows XP Pro on an Acer Laptop, with a 2.93GHz processor. The
screen is faulty on the Laptop (Many vertical coloured lines which makes it
unviewable, and I am using an external screen (Acer AL1714). The Laptop has
the pictures, and the External screen does not. Is there something I need to
do to the External screen or the laptop settings to get the media player
working visibly on both?

Help any ideas??
--
Confused of wherever??