After the reinstall and set up, I scanned all movies and TV programs on my NAS and all was working well on the HD screen. Shutdown and powered off and on and it started up fine. Shutdown and powered off again and swapped to the 4K screen and I'm pleased to say it started up fine.
I can stream a 4K movie from my NAS and it plays perfectly. The Pi did reboot when I tried to jump forwards in the movie but I can live with that in alpha software.
Very pleased with the outcome.