I think this is an issue with my computer power/memory leak/etc but it may be worth noting.

Sometimes the AI will set up something that causes a crash regardless. An example I saw was a battle around Vindobona - there were three full stack (huge unit size) Eleutheroi vs 2 full stack Sweboz that the AI repeatedly sent to battle through a seige.

Regardless of my actions the game always crashed when it tried to resolve that battle. I then manually moved all of those stacks elsewhere on the map and the problem went away.

So, it may be worth playing without the fog of war just to make sure that there aren't AI caused crashes.