Go back to a previous turn save. You do save only at the beginning of each turn, correct? Late turn saves are notorious for producing save game corruptions. If you always save each turn with the same name, you are asking for trouble if one gets corrupted (because it will likely carry over into subsequent saves.) Obviously, your present save game is corrupt unless you have corruptions in some underlying files. You might get lucky and somehow slip past the corruption with an in-between battle save, but it is a longshot.

Since it crashes on you once every 10 hours or so, you need to do periodic saves with new names at the beginning of the turn. There are some memory leaks in the game, but it is more stable and less crash prone than MTW/VI was.