I don't know if it's a bug, but [win_up] doesn't work. The Windows-Key remains pressed after eg. [win_down]L[win_up]. So, my PC gets locked, but the win key remains pressed. If I now unlock my PC and press "L", my PC gets locked again, since the windows key is pressed (vitrually).
My guess is that windows ignores the win_up keystroke because the PC is locked. Windows does a lot of inconsistent things like that. I'd recommend using: