Hi,
Layers palette in AutoCAD for Mac behaves differently than in AutoCAD for Windows. For example in Windows version you can activate Layers palette, hit Enter and this will create new layer, but on Mac - not.
Don't know is it a bug or a feature, but Layers palette on Mac doesn't allow to rename layer until you hit Enter after you type new name. You can use comma to create new layer without affecting previously created layer name if you hit Enter (Return) than hit it again, then hit comma key on keyboard.
Maxim