I discoverd that my xorg.conf file was deleted after I upgraded to Kubuntu 15.04. In my case I just created the file
/etc/X11/xorg.conf and added my driver like this: Section "Device" Identifier "Configured Video Device" Driver "radeon" EndSection Worked well for me, perhaps it can help someone. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1450228 Title: plasma screen flickering To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/plasma-desktop/+bug/1450228/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs