I have this problem as well using the i810 driver. I can preview whatever screensaver I like in full-screen preview mode without any issue and I can run screensavers from the command line, but I cannot get it to do anything except fade-to-black either on timeout or via "activate screensaver" from the "lock screen" panel object.
-- gnome-screensaver fading to black screen rather than saver https://launchpad.net/bugs/61929 -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs