I hate to be pedantic but this is still not a question. In the English
language most questions start with a word that begins with "W" and they end
on a question mark, e.g.
Why is my video running so slowly?
What could cause this?
What can I do about it?
When will Microsoft issue a faster media player?
Fortunately "smlunatick" guessed what you wanted to ask and gave you an
answer that might resolve your problem. We can't be sure.
I did not completely give a solution. I will now:
386MB of RAM -- Add more more RAM. This might not be enough RAM to
play the MP4s, when other processes are also running in "background."
GeForce 2 MX -- Extremely old model of an nVidia video card. Usually
with limited video card memory. Replacing the video card might help.
Celeron 766 MHZ -- A slow processor.