Thanks.
I seem to have tracked down the problem to my video card RTX 3080.
It seems that ANY view requiring Real time raytracing (I.E. wall materials) crashes the software.
I tried it by rendering a quick house sample using Physically Based (Ray Trace) and it crashed.
Using preferences and disabling GPU Ray Tracing solves the original wall problem, "But Now I cant use Real time raytracing"
I'm wondering if my RTX is no longer supported in X17
Edwin