AutoBot: SuSE configures sudo by default that you need to use the root password.
Do you use /etc/passwd & /etc/shadow for authentication, or NIS or LDAP or AD?
Is it only root that can't log in or is every user effected?
Do you have ssh configured? Can you log in remotely?
Can you log into the first virtual terminal (vt/0)? Press [CTRL][ALT][F1] and try logging in. It is possible that root logins are restricted to certain terminals. (configured in /etc/securetty)
Did you change the locale (e.g. LC_ALL) of the system so that the character codes for the keys you press are different now?
If you have physical access, you may need to boot up with a live CD or the rescue mode to fix it. First try booting into single mode by entering "S" as a boot option. You will be asked for the root password, but maybe it will be accepted, depending on what the problem is.
I don't know which SuSE version you have. Once I accidentally didn't give a root password during and there was a problem with a hard drive. I had to boot up with a live CD, mount the lvm volumes and copy my regular password hash (in /etc/shadow) to root's so I could log in. Zeroing the root password would not work.
It is possible that you have a problem with the root partition. The system can't log you in if it can't read /etc/shadow.
Last edited by jschiwal; 01-18-2010 at 03:01 AM.