I have upldated Lightroom Classic to V.8 and still having major issues. It causes my Mac to shutdown, restart or freeze.

Please give your Mac the "once over"! Run the free Onyx (https://www.titanium-software.fr/en/o...), reboot. (In Onyx just run everything in the Automation tab). Run Disk Warrior if you can ($120), (https://www.alsoft.com), reboot. If you can’t do Disk Warrior, at least run First Aid from Disk Utility. Also just doing a "Safe Boot" can clear out bad caches (restart, hold down shift until you see "Safe Boot" on the screen, wait until it boots fully, then reboot normally.)

If that doesn’t work try launching Lightroom from your other (admin or test) account, with a new catalog, as a test. Does it run OK? If it does it may be a corrupted preference in your Username/Library folder. Check The Lightroom Queen site for instructions on how to reset your preferences (https://www.lightroomqueen.com).

No problems here, MiG. (Well, actually lots of problems, just not the ones you report). Keep Activity Monitor open on your computer and monitor memory — you could just not have enough RAM for what you are trying to do.