The game crashes during the Inferno campaign – mission 3.

Yesterday, I was able to load this mission from the menu without any problems (I don't save). Even the "Archers Upgrade" ability, which shouldn't be in version 1.5, didn't cause any issues. If no one else has reported this bug, it probably means the problem lies with the hardware and/or the operating system. The chance of a faulty Heroes disc is very low. If the hardware is fine, you should try reinstalling the operating system.