Why do my Objects show up black in Cinema-4D?
This can either be an issue with OpenGL and you may want to disable it in the program settings (under "File) to test if thats the issue. Or you may have disabled the standard infinite light that is present in every new scene until you add your first light. Add an infinite light from the lights menu and see if that gives your objects some shading.
Also try what @Bart Arondson said and look if you have the "Use Color" option enabled and set to black. If yes set it to "off".