I'm sorry it's really hard to understand what cause such a bug. We still don't have a clue what it might be. Some computers just don't want to play our game well. I hope you will be able to refund the game. Please do so, don't torture yourself. There are plenty of let's play videos on YouTube you can watch :)
For the next game we bought another engine. Stable and with great support with a big portfolio. I hope our next game will be much more stable.