[K12OSN] Help -- Cannot log in as root.

[Krsnendu dasa]

All of a sudden this happened. When I try to log in as root at the
server, at a thin client, I get the message "The system administrator
has disabled your account." I also can't connect through PUTTY or
through NX. What causes this and how can I fix it?
I can login as a regular user and run system commands through gui when
prompted for password by gnome but I can't su at the command line.
I was logging in as root no problems this morning. I have not done
anything on it since I logged out as root earlier today.

I tried rebooting but I still can't login.

A similar thing happened on an identical computer at a different
location yesterdat, only I can still NX and ssh in to it.

What to do?

K12LTSP6