Although I doubt this is the reason for the NAV/GPS Switch texture, as I checked it out last night after I received your email (I actually thought it might be the problem), you may have the Preview DirectX 10 checkmarked (the box is ticked). Go to the Menu > Settings > Display, and on the right side under Global options you will see a box to the left of Preview DirectX 10. Make sure it is unchecked (there is no tick in the box).

That will/should at least stop the fraction of a second a Blue mix of textures when loading the 727.

Note. The only time I have had success with the Preview DirectX 10 settings, was when I used a program made by SteveFX called DX10 Scenery Fixer (it isn't installed at the moment, so I do not have Preview DirectX 10 checkmarked). I'm not even sure if this is available any more, but it cost me $AU37 back in 2013.