Pherhaps its the following Problem: If you make mission part "b" bevor "a" than you cant play "a" Anymore because the gamecrashes when you go to "c", because for "c" its needed that you have done "a" and "b" before! That happened for example in the city, where you have to destroy the Tank! And if you destroy the tank, than find the mines and than go to facility, the game crahes and system too. Than you have to play the whole level again......hope to help you......
