Are you are running Hyper-V and trying to lock down your computer with Scancode Map to assign a key to do nothing or simple reassign keys and don’t get it work? It is probably because you are running the virtual machine in enhanched mode, if you disable enhanched mode this will work as expected.
If you want to lock CTRL and ALT, paste the text below into a .reg file and run it
Windows Registry Editor Version 5.00
For more information regarding Scancode Map