I have a problem with my G-800 right now. At certain occasions some bug appears. Suddenly it doesn't respond to perf. change or midiset change, and the arranger plays half-bars, unsteady beats and so on. I sent it to my local dealer, but when they got it everything was suddenly OK... I checked today, it was running. But suddenly it could crash again! Could this be a software bug? Is it possible to upgrade the OS?? Any help appreciatet.