I, like a lot of people, found that Medieval Total War Viking Invasion (and I think just the game on it's own) would crash to the desktop (CTD) with frightening regularity. In my case it was bad enough that it wouldn't even show the main menu. After much reading around I found a post about the problem that looked hopeful. It indicated that antialiasing had to be set to 2x rather than application controlled for MTW to run. I checked my settings but that was already the case. As I was in the settings decided to try some others. I found that with the latest nVidia drivers (91.xx) you can leave anisotropic filtering and antialiasin on application controlled. The one that has to be tweeked is vertical sync which needs to be set to "force off". Hope this helps someone trying to get MTW to load.