If you clear certain default hotkey assignments (like the Numpad keys to the 'select slot#' hotkeys), the game will 'fix' the 'missing' hotkeys on startup.
To prevent this, simply assign different hotkeys to that column, using Shift, Ctrl or Alt modifiers for things you wouldn't otherwise use (ie for slot0 you could use Shift+0 or Alt+0, rather than Numpad 0).
