Just in case you're thinking "...could only happen on an Airbus", about 5mins after a dusk takeoff in a 777, all the screens slowly got darker and darker until nothing was visible. I put the A/P in with the hope that it was just a problem with the presentation of information to us and not something more traumatic.
We tried cycling the master illumination control and the seperate display controls but to no avail. Just before we went "MAYDAY", the screens slowly came back to life and there were no further problems or indications of the same. The 'fading out' also happened to the standby instruments, so they weren't much use either...
Filed a report but never heard any more about it - I presume that no unusual data was captured and no faults were found on testing. I think that anything that is driven by more than extremely simple software has untested/unforeseen conditions which occur very infrequently. Maybe a cosmic ray went through the controller responsible and flipped a few bits. Who knows?