I read through the link you posted, and it looks to me as though the game is bugged to a fare-thee-well.

I don't know if you want to go to the expense of dowloading the latest version, it might work better. I played the original MM3 game, and in it there were a few squares just NW of the Tomb of Terror which instantly crashed my computer to a point at which turning it off was the only way out – even the 3-finger salute didn't work. However, the version bundled with MM6 in the MM6 Limited Edition worked perfectly, although that wasn't true for the final dungeon in Swords of Xeen. I was never able to complete that game