I have a PCG-71914L with windows 7 and just got it for about a month.
When I hit the power button, power LED and the Num lock, caps lock, scroll lock light up with green light. But the screen is black. I heard disk activity at the start, and sometimes the fan activity.
Also, if I press the power button again, the battery will show a red light.
Before this problem occurred, I made some changes to the power management and used CCleaner. I'm not sure if this is causing any problem.
Thank you for your help