I recall a flatbed scanner giving this message and looking at the lamp, it had blackened ends so I assumed that was the reason. A new lamp cost more than a more modern scanner so the remedy was obvious.
I don't know the situation re lamps in 35mm scanners but it may be worth thinking about. It may be that the lamp is worth replacing in a wholly more expensive device but, again, it may not be that. Is it possible to examine the lamp and see if it looks as though it's on its way out?