Or even worse, accept your 13 character long password and just truncate it at 12. Therefore the next time you sign in your password is invaild and you have no idea why!
I had a similar experience. I'm based in the UK so I have my computer set up to use a UK keyboard layout. One time, I decided to use the # symbol in my Windows password. The next time I tried to log in to Windows, my password was rejected. I eventually discovered that Windows was using a US keyboard layout until I logged in, meaning that # was in a completely different location on the keyboard and I was typing a completely different character. Of course, there's no option to actually see your password while you type it so it took me a long time to realise that I had to type shift-3 to get that character. I'm used to getting £ when I hit shift-3, that being the pound sign that we user over here.
