Add me to the list of people having this problem. I have also run into others in the game who only experience the crash on this level. I fear I could have gotten the Obsidian Lord achievement a couple times had not crashed. That being said, I understand it is a very difficult thing to pin point and I will do my best to pay attention to when I crash and what is running. If it helps for now I am on an iPad 2 with wifi connection.