Every key I type in the login screen is repeated, so I can't type my correct password! (unfortunately my password is not comprised of pairs of characters)
I recently tried to speed up my key repeat rate via this post but after reverting that change the problem is still happening. It only happens on the main login screen after boot; if I go to switch users the keyboard works normally. Fortunately I've found a workaround through the guest account, but I would really like to know how to get my main login keyboard back to normal!