Cad Monkey, Thanks so much for your post. I was having the same problem. Disabeling Desktop Manager for the AMD Catalyst driver solved the problem for me.
Welcome to the Autodesk Forums Sid-Vic!
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I too have an AMD graphics card.
Using Catalyst Control Center, under the Hydravision tab, to disable the Desktop Manager.
This fixed the problem and AutoCAD menus are as they were.