(Updated September 10th, 2012) In Mountain Lion, when connecting to a locked Mac's login screen, you may get unexpected authentication errors. This is because Mountain Lion incorrectly resets the current keyboard type to US English at the login screen. For the time being, as a workaround, you can to disable keyboard mapping in iTeleport and connect to the locked Mac, unlock it via iTeleport, then disconnect and set the keyboard in iTeleport back to your language, and connect back via iTeleport to the unlocked Mac.