I used Simple LightDM Manager to change login screen images in my Ubuntu 11.10 system. But after I have installed KDE environment this software does not works. Login screen changes do not apply now, it just shows black background with white dots and same login manger instead. I need solution on how do I change this login screen image now.
That will reconfigure lightdm, asking you to choose the default login manager.
If there are still problems, try reinstalling lightdm.