Replying to my own thread! I searched this forum to see if I could find
similar symptoms, and Bingo! The solution was to rename the pictures.pd3
databases, restart Digital Image Suite (Anniversary Edition), and do
rescan of the harddrive for all of the pictures. The database was
rebuilt, and DI is running well, no duplicate folders, and the
thumbnails are now working. I had originally migrated everything from an
XP machine, so I'm not sure if info brought over from XP caused the
problem, or if it was something that just developed over time.
My thanks to John Inzer, whose reply to Judy put me on the right track!