But ... computer freezing and restarting is not something that re-install will fix. The problem is either a bad/corrupted/buggy/out-of-date driver, or a hardware malfunction. Re-install your graphics driver, and run diagnostics on all of your hardware.
I am having the same exact issue since yesterday when updated LRC. My Imac freezes and crashes while editing.
I called Apple today, they suggested to reinstall the macOS which I did....Still freezing and crashing, this must be some bad bug from the new Lightroom version. And now my old Lr doesn't run either. Hmmmm