I didn't think so at the time, but not a caps lock problem.
Debian GNU/Linux wheezy/sid debian ttyS0
debian login: root
Password:
Login incorrect
debian login:
Login timed out after 60 seconds.
Debian GNU/Linux wheezy/sid debian ttyS0
debian login:
I didn't press caps lock between the login and password.
Just in case, I did a second attempt, with caps lock on, no change :-(