Launcher won't show up while in "auto-hide" mode

[Distant Thunder]

Hello, I've been using Ubuntu since Hardy Heron. I'm currently running 12.04 LTS.
I think all needed details have already been provided with the "ubuntu-bug" utility, so I will go straight to the point.

When setting the "Hide Launcher" feature to "Autohide" in CCSM under Ubuntu Unity Plugin, though the "Reveal Trigger" option is set to "Left Edge", pushing the mouse to the left edge of the screen won't reveal the Launcher.
This used to work and does not anymore, I can't say why it doesn't, I vaguely remember having updated Unity at the time (a few weeks ago) before the problem started to happen, however I can't guarantee the exact moment when it started.

I just recall that one day I logged in my Unity session as usual and somehow, the launcher wouldn't show anymore however hard I tried to mouve the mouse on the left edge of the screen. Changing the "Reveal Trigger" won't solve the issue.

Changing the "Launcher Reveal Edge Responsiveness" or the "Launcher Reveal Pressure" parameters also seem to be useless.

Can you please tell me how to solve this ?
Bug reports were proposed to me to flag this as an existing bug, but the problem is permanent on my side, it isn't just "sometimes".

So far I've tried :

The "unity --reset" command, reinstalling Unity through "apt-get remove --purge unity ; apt-get install unity ; dpkg-reconfigure unity" commands without any success.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: unity 5.16.0-0ubuntu1
ProcVersionSignature: Ubuntu 3.2.0-31.50-generic-pae 3.2.28
Uname: Linux 3.2.0-31-generic-pae i686
NonfreeKernelModules: nvidia
ApportVersion: 2.0.1-0ubuntu13
Architecture: i386
CompizPlugins: [core,composite,opengl,compiztoolbox,decor,vpswitch,snap,mousepoll,resize,place,move,wall,grid,regex,imgpng,session,gnomecompat,animation,fade,unitymtgrabhandles,workarounds,scale,expo,ezoom,unityshell]
Date: Thu Oct 11 13:46:13 2012
SourcePackage: unity
UpgradeStatus: Upgraded to precise on 2012-04-26 (167 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Carlo de Wolf (wolfc)]

Installing nvidia-experimental-304 fixed the problem for me. (As suggested on https://bugs.launchpad.net/bugs/1057000.)