Have found a few threads on this but none with my exact symtoms. macbook pro A1226 will not start-up 1) Pressed on button , no chime and black screen 2) Press S + Return 3) Turn off by holding down off button 4) Turn and get chime, but still black screen 5) Turned off again, After that, the cycle 1-5 repeats. On a couple of occasions, I did get a white scrreen with apple logo, and a progress bar... but it went nowhere. Have tried resetting the ram, with no luck. I have heard about a nvidia probem which apply to my machine. Would appreciate some advice here.