every time I close the lid on my labtop I get a black screen, even though I've selected "Don't suspend" when lid is closed under the Power settings. Cursor don't show, just a lighted black screen.

I tried fixing the black screen by installing the recommended NVIDIA accelerated graphics driver(version 319), but then my Mac wouldn't boot, so I reinstalled 12.04.

When I manually suspend through option in the upper right corner it works fine. Just not closing the lid.

Any ideas on how to fix this?(I'm a Linux newbie) Thanks