Bob, I've solved it by completely rebuilding my computer, re-loading, updating all drivers, all software. It works now. Wish I could be more helpful regarding what made the difference. A couple of things...my new computer uses all SSD drives internally for windows 7 and data. I also had my data SSD connected to a SATA 2 connector instead of the correct SATA 3 connector; likewise, had my OS SSD connected to a SATA 3 connector instead of SATA 2. Reversed these in process of rebuilding, but don't know if that is what solved it, as MC17 recognized the DLNA devices before I reversed, just wouldn't play. Also, I might have found and installed a more current driver for the motherboard along the way, not sure. Again, wish I could be more helpful. There were so many variables along the way between installing hardware and software. Bottom line, problem I assume was not with MC17 but with my setup. Working beautifully now. Making regular backups so I can restore if something goes bad again.
Thanks for your patience, and help. Oh, by the way, all my music files are either .M4A or .flac