Game crashes: questions and answers.

The problem is this: I downloaded Heroes of Might and Magic V: Tribes of the East, installed it. When I launch it, it doesn't start; the computer just freezes and makes a loud noise like a tractor, so I have to restart it every time. I tried using the troubleshooting tool, and now the computer doesn't freeze, but it just kicks me out of the game back to the desktop. I downloaded the game from three different sources.
Does anyone know what the problem is and how to fix it? Maybe I'm doing something wrong... please help.