Comment 36 for bug 1357090

As you indicated, no combination of settings seems to help, and you'll probably continue to see a similar issue without xfce - power - manager or light-locker. This seems like it is an issue with X or the kernel. For your sanity, try setting logind-handle-lid-switch to true (default), uninstall light-locker, install xscreensaver, and reboot.