I upgraded to Lightroom CC from version 5 just a few days ago. When I start it up everything is fine but as soon as I start working it blacks out (or sometimes a grey screen) and the message "Develop does not answer". This happens every time.
Thanks for answering. I think I have solved it now. Exactly what you proposed, it was the GPU that gave me problems. With new drivers and a bit of tweaking I got Lightroom going.