Hmmm - I have taken no apparent action to address this but mysteriously the startup problem has gone away.
Somebody updated something that was messing things up.
Lesson re-learned for the umpteenth time:
Don't upgrade your OS until it has been around for a few weeks! ))
Question for the mods:
Why was this thread pruned back to the original post?
Responses that were about different issues were branched to separate threads.