A great thank you to all who have made suggestions. I have tried 4.0, 4.4.1, 5.1 and 5.5, some of the zip files, with and without my .octaverc file and the GUI fails to appear or crashes immediately in all cases. I have installed 5.2 on another laptop which I first updated to have the same version of Windows 10 and Windows updates as mine. Octave 5.2 works on that machine. Thus it is likely that the problem is caused by some conflict with some other software or hardware on my laptop. I can run flatpak octave 5.2 or octave 4.2 on mint 19.3 on another PC. On my Windows 10 PC, the CLI version worked in all installs. I can, therefore, use CLI mode in Windows 10 or Octave mode in Emacs which also works.