Unable to use autohide launcher in 12.10

I upgraded Ubuntu from 12.04 to 12.10. Everything went well but the launcher does not show when I move the mouse cursor on it.

My computer is HP Pavillion p6582l, Core i5, 4GB of RAM, Nvidia GeForce GF315 3D graphic card.

Please tell me how to fix this problem.

Solved adding

Option     "ConstrainCursor" "no"

to Section "Device" of xorg.conf (if xorg.conf is not present, create it with "nvidia settings") as described here.

Try the easiest way first.

Go to System Settings → Appearance or just press the super key (windows key) and type "appearance".

In the window that opens, go to Behavior tab and switch Auto-hide the Launcher to ON and Reveal Location to Left Side as shown below. If this doesn't work, do let me know.