Thanks to ALL. It has only happened once since my original post. That's in a lot of Random playing, so...improvement. Jeremy, I haven't tried to do anything when it happens except Stop/Play and start random again. I have been able to replay the track again, before pressing Stop, and it stops again after the replay. I don't have Sonos speakers, Fred. And, Paul, I have always used the Next button when this happens. Although I don't wish problems on anyone I was glad someone else had it happen (Sorry, Raysph). Annoying, yes, but a major inconvenience, no.
As many another poster has said, the amount of technical know-how and willingness to help on this forum is astonishing and well appreciated.