Thanks for the VLC Player Idea, I have already done this and a couple of other MP4 players with the same outcome.
I have updated codecs and checked for virus etc to no avail.
I am begining to think it is within the WD Pasport system not handling MP4 for some reason. I suspect this because I have tried the WD pasport on another compter with the same outcome.
I am awaiting some WD Tech guy to reply, his having evaluated the videos I posted to WD. I hope they reply, and have an answer.