Just to followup, Adam responded quickly and he determined the cause of my issue wasn't the OS but a corrupted database. He outlined the process in MM to rebuild the DB, and having done that everything is fine now. To answer Barry's question, I have a 4TB Samsung SSD installed inside the BDP3 for my music files, and I have that drive also set as a scratch drive.
So once again, thanks to Adam and James and all at Bryston for the first class service. I don't take it for granted.