Hi MrLightman,
That's not really normal indeed, it could indicate that you have a graphics issue with your card/driver on your pc perhaps. Might I ask, is your pc up to the task, graphics-card wise?
There isn't really any chance in the patch to this kind of thing at all that I am aware of. Perhaps you could post your dxdiag/pc specs, so we can have a look at what migh possibly be wrong.
Regards,
Fred