Have you tried deleting your prefs file? A corrupt prefs file can cause all sorts of funny things to happen. Sometimes it can be the prefs file that is left in an inconsistent state.
No, never thought of that.
I will, especially since I have not done any extensive work in them. I'll review the process, probably just rename the file and then report here after several sessions of LR since it is not reliably every time I quit/restart.
Thank you for your thoughts and getting the idea to me so quickly!
I renamed the file, saw that LR reverted to original look and feel OK at next session.
It closed and reopened with no problem. I imported, developed and moved photos, exported a couple and quit with backup/optimize.
Did another session with less work, quit with no backup.
Did another session with more work, more moving among subfolders, etc. Full backup.
All above with no 'inconsistent' message.
Next opening ~ got the message. It takes maybe ten seconds at the most, then opens and acts as usual.
Although I have not found any deleterious effects on anything, it is just a tad unsettling...
Thanks for your time and attention to this.