I'm experiencing this as well. Starting gnome-screensaver from a terminal works, but I can't work out how to add gnome-screensaver to run by default - it looks like Startup Applications doesn't exist in 14.10?
I'm experiencing this as well. Starting gnome-screensaver from a terminal works, but I can't work out how to add gnome-screensaver to run by default - it looks like Startup Applications doesn't exist in 14.10?