Hi,

No, this is not cleanscreen, something in your user account on Mac prevents from copying necessary support files to the AutoCAD application support folder inside your Home Library folder.
This problem was already discussed here on the Forum. The solution was to copy necessary files manually. Try to search Forum for "Missing menu and Tool Sets palette "
You can also try to create new user account on your Mac, login to it and launch AutoCAD. It should work properly in new user account.

Maxim