Posted by Jason O'Neill on September 30, 2006 at 09:57:48:
I just got a QS8.1 in good condition. Ocassionally, it will not boot up, LCD light comes on with black squares at top only. It's frozen a few times, sustaining notes after pedal released. It has read "INVALID COMMAND" or something to that effect when freezing. Also, the tone of sound seems to change shortly before this happens. Any suggestions?