Thanks Fireali. I started getting same problem on my freshly installed OpenSUSE 11.4
I logged on as root, created a new user, copied files from old user, and deleted the old user.
that saved the day for me.
but this seems like a bug, and perhaps a fix should be available that prevents this.
This usually happens if you log into a GUI as root. root grabs ownership of some important files in user’s home and prevents the user from logging in. Change ownership back fixes the problem. And this has been around about as long as GUI’s have been added to Unix’s. So I doubt it will be fixed soon
the files are usually: ~/.ICEauthority and/or ~/.Xauthority
So the general rule is never log into a GUI as root. You can become root with su sudo kdesu gnomesu but do not log into the GUI as root. Unless you are prepared to fix things afterward. You can also login as root to a termianl session and use yast or other command line tools. But not the GUI!