Is it possible that the "normals" are set improperly?
In MED, move your mouse over the menu strip until you come across one that lokks like >|< . This is the normal flip button. If you let your mouse hover over it, a tooltip should say nomals. Select the entire model and then click the normals button. It will turn the model inside out, which might make them outside out for you.

Normals just set which direction the faces of your model face.
Cheers.

Mark