Root password disappears at every login, was "Cannot login as root"

[M. Fioretti]

On Sun, November 16, 2008 7:00 am, M. Fioretti wrote:
>
>>>> I get the login prompt, type root, after a few seconds I get the login
>>>> prompt again, the pc never asks for a password.
>
>
> after studying the dmesg output... I had an inspiration and disabled
SELINUX by
> adding "enforcing 0" at the end of the kernel line in grub.conf.

that made the password prompt appear and I was able to login as root
several times.

After that, I installed with yum at the command line X (with nvidia
drivers from rpmfusion) and then did a

yum groupinstall 'Gnome Desktop Environment'
yum groupinstall XFCE

without noticing any errors. Then I set inittab to runlevel 5, rebooted
and got the graphical login screen. Logged in as root, found everything OK
in Gnome, created a normal user and rebooted.

Since then, root password doesn't work anymore. If I login as the other
user it works, but if I login as root or type "su -" I get a "password
incorrect" message. If I boot in single mode and set again the root
password I get "all authentication tokens updated successfully" but the
password doesn't last.

Next login as root, I get "password incorrect' again
Any idea on what the problem could be now and why is only the root account
having it?

Thanks,
Marco