It happens only when the computer is plugged on a power source. The situation on battery is not the same, knowing the computer goes to sleep.
When I close the lid, the computer behaves correctly:
- Screen turns off
- Does not go to sleep (front light stays on and does not flash)
- Still can hear fans
But when I open the lid:
- The screen turns on...
- ...and turn off about 2 seconds after
I can see my desktop background, and the login window for 2s, and after that the screen becomes black (actually it turns off, it's not backlighted black).
The little trick I found is to reduce the luminosity thanks to the F1 key, and then increase it again to come back to maximum luminosity.
Computer specs :
- Macbook Pro 15" bought 2 months ago
- It came with OS X Lion already installed
- I choose the screen resolution option (don't know if it matters)
It's not really handicapping since I found this little trick, but it's a little bit annoying to have to do that every time I open my Macbook.
UPDATE : Check out my related question here : How to prevent the screen from turning off when I open the lid? It seems that the problem has been solved by Mountain Lion.