Can I have some help here please? I'm using a brand new iMac 21.5" with an Intel Iris 6200 Pro graphics card and 8GB ram, straight out of the box. The game is on the default settings. I have an X-52 joystick. The only thing extra is the X-tracker plug-in, which I've now removed. I get sound but no screen. I know this is a Beta version but at the moment it's no good to me and it's no good to you guys at LR.