Thanks for the link. I also had interpreted incorrectly. I was originally under the impression (incorrectly) that the MIDI was what was doing the stuttering.

Q1:
I'm presuming that the song plays OK as long as you don't play anything on your keyboard. Is that correct?

Q2:
Have you tried a "Return To Factory Settings - ALL", from the Options menu? (I can't recall above if that's been suggested). You would have to then reset some values.

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