A THREAD FOR NEWCOMERS!

That would be the best.
But, if you don't really want to, you can try installing the game from
here.
Maybe it will help?

I have this SoD... as far as I remember, the main ISO file is archived in RAR... but for some reason, it won't install on my computer.

Added after 4 minutes

Heroes 3 crashes because of incorrect operation on multi-core systems. You just need to launch the game, minimize it, right-click on the process in Task Manager, and select "Set affinity." Leave only one checkbox checked, and that's it.

I don't have that command in Task Manager... there's no command even remotely similar when I right-click on the game... sorry... I checked in Applications...))
Well... I checked only core 0... it lasted a little longer... but still...