Scripts must be always activated in multiplayer or hotseat otherwise many things do not work properly.
Use MMH55_64.exe so the game wont crash on big maps. The old exe cannot handle more than 3GB of memory.
That guide in the upper post explain all tweaks to go around crashes.
Let me know if it happens again (also tell us under what conditions - what exe do you use; what mode - Hotseat or LAN?; how many computer and human players; the size of the map).