Thank you for posting the save game. It makes it much easier to debug problems. I can reproduce your crash, and I have good news and bad news. The good news is, your crash is already fixed. It is due to the attack animation on the assault cannon unit. I think as soon as you attack a BG assault cannon, or it attacks you, the game will crash.
The bad news is, the earliest patch available to solve your problem may also break your save game. You can update to 1.6.1c at
this post. If you do, I am 90% sure you will be unable to load your save game. Because we change so many things in one release, we have not tried to maintain save game compatibility. Try that patch and then try loading your game. It may work.
There is a more recent patch, 1.6.3 at
this post. Because this patch adds a unit, I guarantee your save game will not work.
If you really want to keep your save game, perhaps deliverator can break out the assault cannon fix into a separate file.