Hats off for your patience when I was being grumpy
Just in case it helps anyone else getting this type of unexplained crash, I recently removed my Nvidia GPU and am using my onboard graphics - since then it hasn't happened again...
May be a coincidence but I suspect not.
Not sure if my hardware is faulty, or perhaps driver problem.
Anyway, check your hardware stability, if possible troubleshoot by taking out unnecessary components.