Past few days I've been getting this problem. When I completely shut down my Macbook (regular 2009) and turn it back on I see the white light only and black screen. Nothing works.
This has happened two times and I pressed the power button for 10 seconds to do a PMC reset and it actually turned on and Today I had to press SHIFT + Power button to turn it on.
Do I have to do this every time when it's off? What does this mean? Is my Logic Board going bad?