Your question was, "In other words, you hit PLAY and the track countdown in percentage happens up top in the blue bar, but instead of the song playing it ends iwth those error messages?" Yes, that is correct.

And I did a "Return to Factory Settings" under the Opt menu, choose the 2nd button choice.

You are right when you said, ".MGU indicates a songfile that has notes on the Melody track. A song with a Melody. .SGU means a song with nothing on the Melody track. To my knowledge it has nothing to do with the Solo track." I mistakenly said "solo" instead of "melody". But as I indicated, I have not put any notes on the melody track.

Thanks for your suggestions,
JL