I suspect the video card is bad. On my original problem, upon start up, the screen was a dark greyish color. I immediately connected an external monitor and as soon as I plug it in, the laptop screen returned to normal. It works fine for the first day but if you leave the computer off more than 24 hours, the dark greyish screen returns and as long as I connect an external monitor, it works fine.
I also completed the suggestions mentioned in your last reply (re-seat the ram modules and hard drive, and the keyboard) upon connecting the external monitor the first time.
I am duped right now on this laptop and I also replaced the harddrive with a known good one and the problem is still there. I also updated the BIOS, re-installed the drivers, and replaced the RAM. The only thing I havent tried was the video card.