If you're playing the Korg module from the P-200 and getting the same effect, there must be something in the key switches, under and inside, that causes more than one key switch to close when you press just one. Time for a thorough cleaning of the inside of the P-200.Especially the keyswitch area. If it's still under warranty you may want to have it done by a shop.A very delicate vacuuming and if the actual switch contacts are exposed, De-Oxit or TV tuner cleaner, NOT SILICONE.mn