[Guest]

I think canonuk explained it best in another post - the bigger kb file size DOES have more aircraft FMs in it. The way the game works, is that you need to have the FM for that relevant plane in the buttons file. If it does not have that info, you will get a 60% CTD. It is, however, ok to have extra AC FM'data in the buttons file, even though you don't have that AC in your game yet. The game will not crash with extra data in the buttons file, but WILL crash if you are using an AC that does not have its particular data in the buttons file.
This issue is heading towards being a bit of a headache for the whole community, methinks... 8)