If your game crashes while the battle is still loading then I don't know the cause, I never looked into it. Crashing while loading has to do with files/code, so that could be the animations, textures, models, or the coding for it. If COW stuff works for vista/8+ someone can send me the relevant unit files and I will check it out (I assume model and texture code are more likely the cause than animation code unless vanilla M2TW elephants cause a crash for you). Or post the end of a crash log with trace enabled when your game crashes. Or both.
If your game crashes at the start of the battle, one solution is to change all the battle_wait timers as I did. But I did it for xp/win7 not vista/8+, and TATW doesn't have it for either really since the timers all vary dramatically in certain situations. I don't play vanilla though so I have no idea about crashing in vanilla.
If it crashes during the battle only a log will tell you what it was.
I personally don't have any issues with crashes so I am not about to go out of my way to fix it, but I'll enjoy looking into it if someone makes it convenient for me. No one has so far that I can remember.
People with vista/8+ usually have a harder time installing mods too from what I have seen. Though it isn't directly relevant, it does make me want to blame Windows
. Of course M2TW wasn't made for vista/8+ though so it is wrong to do so I think.