I have a 17" macbook pro out of warranty. 2009 macbook pro 5,2 @ 2.8ghz Sometimes the screen goes black and a couple seconds later it goes back to normal (time could be fraction of a second to over a minute). The frequency is erratic. It happens on both the nvidia 9400 and 9600. During the blackouts, the backlight stays on, just the images are gone as if the video link is cut. It never happens during boot up sequence. Blackout only when fully booted up and in the OS. The fact that it only happen when fully boot up suggest a software problem. However, the erratic nature of the problem suggest a hardware problem. Blackouts on either the 9400 and 9600 suggest it's neither because the probably of both GPUs failing is very low. Probably not the LCD cable since laptop is stationary when it happens and problem is not reproducible when shaking computer. Cannot be the LCD since it doesn't happen during boot up... and full circle. When it's blackout, if I press F4 dashboard button, the dashboard animation appears for a fraction of a second and goes back to black. I think it's the OS. What do you guys think?