I just had this same crash however I noticed something else odd before it happened:
I was carefully surrounding an unsuspecting alien planning my attack as everytime I looked to shot it the chance to hit was 0. Then after several turns I realised it was not moving at all. It didn't move, turn, shoot or rection fire at any of my units. I thought this very odd but assumed it was a glitch related to the 0% hit chance at 4 tiles away so shot at it and the game crashed.