Just posting in case someone else Googles this problem. I have a user on AutoCAD 2010 who complained that it would not start up, and instead would freeze with a grey interior window space. I started playing with the registry, and changed HKEY_CURRENT_USER\Software\Autodesk\MC3\MC3OptIn DWORD value to 0, and the application now starts fine.
![Autodesk Design & Make Report](https://forums.autodesk.com/t5/image/serverpage/image-id/1350519iCB55845EBFC43016/image-size/large?v=v2&px=999" "Autodesk Design & Make Report")
