@RM9981 and others ... outstanding effort and thanks! Fix worked (to remove Norton) although I did have a few more restarts while I had a USB drive (WD MyPassport Ultra 1T ca. 2015) attached ... after detaching and restarting it was stable ... I downloaded and ran the WD Utilities and Security apps (did not appear to do anything special) and since then let TimeMachine run and so far no restarts ... this does not prove anything, just an observation So was it legacy system extension issues with Norton or with my older USB drive/software ... or both and does that explain the inconsistent results different people has attained? Hoping for Apple and/or Norton to fix to allow Norton to be installed again