AFAIK Steam downloads a different Medieval_TW.exe which is very small and it's hard to notice the download process because it ends nearly immediately. This file doesn't interfere with saved games so you don't have to start a new game to see changes. Of course it was only an option not guaranteed solution (but still worth trying). To get back to the newest patch just repeat all the steps and choose "NONE".
I've tried the saved game you sent me but it doesn't crash for me. I checked the logs but not even smallest error appear so the problem is probably hardware or driver related. Try update your drivers (video card mainly). If don't know how to do it
Driver Booster will help.