su not working

["Javier Vasquez" <jevv.cr@gmail.com>]

Hi,

I'm used not to login as root, specially under X.  Instead, when
required to edit a configuration file, or do something not planned
under sudo, then what I do is to "su" and then provide the root
password.

The problem is that the root password is never recognized, so I can't
su-to-root ever, from a non root user...  This is what I always see:

% su
Password:  <root_password>
su:  incorrect password

% su root
Password:  <root_password>
su:  incorrect password

Is this known already?  This sounds particularly unconfortable under
X, since it's supposed to be unsecure to start X under root.  Is there
a work around, :) ?

Thanks a lot,

-- 
Javier