Game crashes: questions and answers.

Hello, I've searched the entire internet for a solution to my problem, please tell me what can be done here: I bought HoMM 5: Tribes of the East on Steam, I haven't installed any mods/translations/maps, my hardware is from 2013, I have the latest drivers, and I'm using Win 7-64. It is completely impossible to load the game from a save on a large, generated map. I create a map, save/load on the very first turn, and I end up on the desktop. It happens consistently. It would be understandable if it were a pirated version, but how is it possible that in the licensed version, the ability to CREATE such maps exists, but it's impossible to PLAY them?