Screen blanking triggers login screen

[Lee Hyde]

Following a recent update, whenever I switch my display off via /xset dpms force off/ the display blanks (as expected), but a few second latter the display's backlight cycles on and off a few times before displaying the nVidia splash screen and then dumping me at the LightDM log-in screen. When I log back in it becomes clear that I was never actually logged out (so I suppose it would be more accurate to call it the LightDM switch user/lock screen). I do have Light Locker installed, but it's inactive and I have Saucy's default lock screen (gnome-screensaver?) set up for the time being.

I'd love to provide you with more information, but I don't quite know where to start with this one.

Version Information:
Ubuntu 'Saucy' 13.10 x86-64
nVidia 331.20-0ubuntu1~xedgers~saucy1