Open the rear of the operator panel. At the top of the screen there is a ATA memory card that runs the Mapps. Might be a small cover over it, but you can still see the card. There is an eject button next to the card. With the power off, eject the card and re-seat it.
If that doesn't help, you may be getting a mapps processor overheating, check for dirt and if it has a fan on the CPU cooler. The mapps is all behind the screen. You should back up mapps parameters on to a card now just in case, if you use the Caps programming. You won't loose any fanuc data by messing with the mapps panel. If still nothing, have the service company come out and do a software upgrade, takes less than an hour.
If the mapps panel itself is dying, new ones are a retrofit to Mapps 3 or possible mapps 4. Usually when a MAPPs panel dies though, they just go.