I have a replicable situation where if The Necromancer manually fights a battle, subsequent campaign map turns will exhibit a bug where selecting The Necromancer's army will automatically crash the game.
More specifically, this hang up is prevalent on the Minas Tirith Siege map. If you autoresolve, The Necromancer's army will be able to be moved around. If you manually fight, then the crash will occur after the battle is won, and have the rounds progress until the next turn. This may have to do with leveling the Necromancer, or building persistent units. This is a pretty reliable crash.