It sounds like a sys-ex message to turn a drum track into a normal track. Then , if the PC# got sent before the sys-ex, keyboard is likely to play Piano (#1) as a default sound.
Can you copy the sys-ex message and post it here (should be fairly short)?
Perhaps I can take a look at it and see what is going on...
Diki, if you download the SMF I posted on Roland arranger...it will be the first sys ex line..open in the G70 sequencer..