Oh no! Something has gone wrong.

Hi,

About 6 months ago, I've installed Fedora 17 (Gnome 3) on my machine (multi - boot with Windows 7) .. Everything went O.K. and no problems faced me although I'm pretty new to linux.

A week ago, I've installed Xfce desktop to try it. and things went smoothly. Yesterday,I've installed xfce4-xkb-plugin to change the keyboard layout using this code:

Then, I logged out the XFce session and tried to log in again, but I couldn't. I forced a reboot and sadly the wild "Oh no! Something has gone wrong." screen appeared..

I pressed Alt+Ctrl+F2, and uninstalled the plugin, but nothing changed after reboot, and now I still have the same problem of the "Oh no!" screen.

Any solution to diagnose and solve the problem?