> I was having similar issues with some machines not powering down after
> shutdown and that solved it for me. In my case, I simply set that as the
> exit command for my window manager, and I have no idea how you might go
> about doing it in a desktop env.
You'd type the command in an xterm and press enter.
Yes, you can always do that... I was talking of something more efficient and user friendly. For example, in my case, I use Fluxbox and simply put that command as one of the entries in the main menu. This way takes me two clicks (or key presses using keyboard shortcuts) to shutdown. Maybe you know how to add a custom entry to a menu of your desktop environment.