Such problems are the reason why I never use anything but ASCII letters as passwords (if the system doesn't enforce arbitrary password policies). I'd rather have a longer ASCII-only password than a shorter one I might not be able to input.

There's also the issue that often you are not sure what keyboard layout is current enabled and even such unsuspicious characters like ! or # are on completely different locations on different keyboard layouts (then there's the z-y swap on German derived keyboards and have you ever had a look at a French keyboard layout?).

You can never be sure if a system locks you out after failed attempts, so I want to be sure that there are as few error sources as possible.