Hi Tom, thanks for your response. It just crashes when I am running CNN training models with the message “the kernel appears to have died. It will restart automatically”. I use tensorflow on other other computationally intensive workloads, and they seem to work fine. I re-installed PyTorch to version 1.3.0 last night and the same thing thing keeps happening, except it seems that the script is still running on my hd. Anyway, I’ll keep experimenting , maybe its just because I am on an old comouter,  a Pentium based one, which seems to run everything else.
Anyway Thanks, Tom
Clive