Ubuntu – Screen locking does not work after upgrade

I managed to figure out a workaround, though I imagine there's a better solution out there. I looked at what was happening when my lid was closed and opened in /etc/acpi/lid.sh and found that xscreensaver was being called upon automatically. Not sure if different laptops have different settings and whatnot - I really don't know too much about this stuff.

In any case, I tried to make it simply obey its config file and not lock, but couldn't figure it out, so I ended up simply deleting the lines that involved xscreensaver. Now everything works great: no locking, and if the lid is closed passed the amount of time which you have set for xscreensaver to start, it'll start normally (and not lock).

I'm still not sure why xscreensaver is set up to be called automatically when the lid is closed or why it ignores its settings and locks when the lid is opened. I also don't get why with my older laptop this only happens sporadically (sometimes it locks every time, sometimes not at all), despite having the same lid.sh file.

I should also note that I'm using Ubuntu 12.04 with Unity, though I don't think that'll make any difference.

Ok I've resolved this issue now, and am posting the solution for anyone else that wants to do the same as I have.

1. xscreensaver needs to be launched at startup via "Startup Applications" (hit Super and type "Startup"). Add a new entry to launch the xscreensaver daemon on startup as xscreensaver -no-splash.

2. You need to bring up the xscreensaver config app. Hit Super and type screensaver. Set the "Blank after x minutes" to your desired amount (e.g. 5 minutes). Remember this value for later. Ensure "Lock screen after" is UNCHECKED.

3. Finally, go to System Settings / Brightness & Lock. Set "Turn screen off when inactive for x minutes" to the same value as you set xscreensavers "Blank after x minutes" setting (e.g. 5 minutes). Then still under Brightness & Lock, set "Lock screen after:" to "Screen turns off".

And you're done! If your system is idle for the set amount of time, the screensaver will kick in, and in the background your session will also lock. When you wake your system, you will find it locked and asking for your password. No ugly 90's login prompts... awesome. The one caveat is that your screensaver will apparently not kick in if your session is already at a login prompt, the screen will simply turn off.