No scenes on the nanokontrol I think, but there are on the nanopad.
Sorry, but the method I described above worked for me without problems.
As biodiode says, your problem may be too many MIDI 'ghost' devices for Windows to cope with. Another way to find them is to open control panel/device manager and check 'show hidden devices' which is in one of the menus (away from home so I haven't a PC to check exactly which).
Device manager will then probably display a number of additional things some of which might be MIDI devices. Delete them and see if that helps. The 'ghosts' are created when a device is plugged into a different USB port than before and Windows has no way to tell if it's a device is already knows about or a different one so loads a fresh driver which then persists in case it's needed again.