@243JohnM, would you mind sharing one of your crash dumps? They're rarely useful to be honest but it doesn't hurt taking a look.
How long after computer restart does the app crash?
Also could you please share the last few lines of your log file, just before the app crashed? The log in your profile directory in .config\log.txt. You will need to have debug mode enabled to be sure all information is in there - joplinapp.org/debugging
Could you send me as a PM with the crash log, named joplin_crash_dump_xxxx.json from your home directory? I think I will disable the feature to upload crash log but they are not really useful and I can't match them to a particular crash report