Just seem to have lost all my general setting for mach3 turn. Now coming up with a 'Quantum' loading screen. I've tried to load a new screen, using 1024.iset, and the simpleturn and turnblue, but the programme crashes every time.

Does anyone have any ideas??

Have you installed Quantum? If so you may need to reasign the location of Mach for the shortcut you are using.
Hood