Sounds like there was an error reading the hard drive on boot up. I used to get that symptom a lot around here until I switched to a different HD. The icons for the AC graphics are stored on the HD in the images directory. The data for the trip and maint screens are stored in the ETACS computer, iirc.
Power off (switch ignition to off), wait five seconds and switch it back on. Should fix it.
Power off (switch ignition to off), wait five seconds and switch it back on. Should fix it.