[DISCLOSURE: standard/basic Forza7 disc running on a basic XB One]
While attempting to create a new design for the Lancia #31 Turbo, the game has crashed 3 times, all in one day. Twice from a fresh re-boot that was not run for races or multiplayer at all; merely editing a single livery.
Design was not too simple, nor very complex, either: Two instances of a native ‘swirl’ graphic(on page 2 or 3 of the in-game decal/vinyls. iirc), and perhaps a half-dozen custom vinyls of simple logos/icons, was all I was trying to use.
I’ve seen liveries with 5-10x as much graphics stuck all over. I was only working for 10-15 minutes.