I have a little difrent problem. My laptop(toshiba 7 year´s old) blacks out 1 sec after I lift up the screen, and then if goes black. If I close it and open it again it works for 1 sec again, and then goes black again. After a restart I could se a check with numbers going up til 5000 and somthing when it stopped. I couldn´t see what els it sayed in the 1 sec or les it shows. But when i connected the pc to the tv, i could emty all important stuf to an external HD. 1 month ago I had the same problem as the others here. And it was resolved by doing the same thing as they did.
Did you check out the tiny lid switch? Sometime they go bad, or stick. I suspect that is not the problem, but it is the first place to start.
Since you see numbers counting, I guess it must be the Basic Input Output System (BIOS) doing a Power On Self Test (POST). Normally, systems would be set to skip this. So the question is, why is the POST counting your Random Access Memory (RAM)? Either someone set it to count the RAM (disabled a quick-boot option in the BIOS), or the system recognized a problem, and is trying to resolve it.
Next, I would try setting the BIOS to defaults. Watch the screen when it starts, to find out how to enter the BIOS Setup (usually the Delete key will work, but commonly an F-key).
If your external screen didn't work, I would say to test your RAM, but it does... There is a F-key on many laptops for blanking the screen, but it won't usually stay blank... And it wouldn't be a driver, since the screen blanks before the Operating System is given control...
Get a really bright light, and shine it at an angle on the screen (with the external monitor unplugged). Can you see see a faint image?
I was looking for the users manual for your model, but couldn't find it. I did find a manual for that series. I believe holding the Fn key, and pressing the F5 key should toggle the "monitor priority" setting. This allows you to set the external monitor monitor as the primary video display. Try that key combo several times, and see want happens.
Tryed the bright light. I can se the background. Should I still default the bios?
I have tryed taken the battery out and holding the power button down for 60 sec. But it is the same. But I noticed that when it was powered up for a wile and I moved the screen a bit, The light came back and then of again.