Switching planes option no longer works-what happened?

[jamesdietz]

Out of the blue, the option of switching to other planes in a mission stopped working .Yes I have it ticked in the realism list & I've tried to solve by re-booting the PC ,but so far no joy.What now-check validity of files? If I do this what should I make sure I save to reinstall?My Campaigns over in Steam seems to get erased when I had to do this in the dim past.I also have the little utility that intensifies the color-I imagine this will have to be reinstalled...anything else or is there an easier way?
Thanks!