I don't think thats a bug, I can make models look that bad in C4D if I turn backface culling on
, its to do with Culling, I've never used Milkshape, but by the looks of things Milkshape (like Truespace) constantly has Backface culling turned on, this is not a bug, it just shows you what it would look like ingame. This means, your faces are really upside down, but there should be an option to flip selected faces, that should solve you problem (has worked for me in C4D and Truespace)
"I want to put a bullet through my f***ing head everytime I think of you!!!"- Slayer