I had the same problem, I was running the game on a pentium E5500 4gb ddr3 GT 710 gpu and when I click Sortie it would just crash, Luckily I had a spare system (intel i3 8gb ddr3 GT 710) and it ran perfectly fine. So there might be a *capatablity* problem in the game. I think that it had to do with my CPU (Pentium) not being able to render or make up the AI. Maybe try a different system (or someone else's) and see if that's works.
