Can't login

I had some kind of nasty disk problems on our mail server. Fsck seems to have successfully fixed the errors, but not everything's intact after the disaster, apparently. Most notably, I can't log in -- either from the console or via a telnet or rlogin session. This puzzles me because /etc/passwd and /etc/shadow have to be intact, because authentication is performed just fine for all users via ftp, and pop3. What's happening is that any time I type a username to log in, the system just returns an invalid login message and dumps back to a login prompt -- I don't even get to the point where I can type a password. Meanwhile, syslog indicates an authentication failure each time you try to log in, no matter what username you try. I've already replaced /bin/login and mingetty from known good installations, with no success. Also, the only things in /lost+found are plain text files -- all having to do with KDE config issues. Anybody have any ideas on what could be corrupted here? Thanks, Jared

How can you see file in /lost+found if your are not able to logon???

Like I said, authentication works for everything else except shell logins. I can access anything on the hard drive via ftp or Webmin. Jared