A problem has arisen... Heroes 5, Tribes of the East 3.1

I'm creating a HotA map - Size = Incredible, Difficulty = Hero, 3 computers. I'm playing as Orcs, and the game randomly crashes (usually after the first week) with an unclear error (as far as I can tell, it usually happens when trying to build something in a town)... and the worst part is, when I try to load an auto-save or any other save file from this game, the game crashes again.

I can play online and in campaigns, and in other HotA maps without any problems.

I need help, because I don't even understand what this strange error could be related to.