In 1.2.0.7, Custom Skins appear as black

In version 1.2.0.7 (it didn't let me choose another version) Custom skins (and only custom skins, not skin pack skins) appear as simply being black. When trying to switch your skin, the Steve and Alex model selections appear as invisible. When trying to join a game with this weird black skin, it says "Invalid or corrupted skin" and doesn't allow you to join a world.