I checked in on the Korg forum here and found a nice piece of advice for Korg Pa4X owners. A owner complained that his Korg was changing voices
by itself while he played. Snoopy, a Synthzone member had this answer
for him after asking if he had left the plastic film on the display.

Snoopy said: "Leaving the plastic film on the Korg can cause static
discharge which in turn can change the voices all by itself".
Very good to know so I am passing it on in case some of you Korg
people are doing the same thing. Take it off, Take it off ! Lloyd

nice tip -

Thanks Lloyd,
I actually left mine on too, thanks for letting us know.

Thanks, your welcome. Lloyd