I have a problem with my HP compaq 8510p laptop: when I start it, the fan starts and the power light is on, but the screen displays nothing. When I insert a bootable hard drive, it activates the hard drive light (meaning that the CD is recognized) but it stops after a few seconds. Same thing with any hard drive: the drive is recognized but does not boot.

What I've tried so far:

• Changing the hard drive or booting with no hard drive (same problem)
• Plugging anoher display via VGA : no display on the other screen
• Inserting a windows-7 CD (same problem)
• Booting only on battery, with battery and power cable, only with power cable (same problem)

So it looks like something is preventing the laptop from booting and displaying the boot menu. Do you have experienced something similar with a laptop ? What could be wrong ?

The laptop is out of warranty. The system used to be windows-7 x64.

Edit: I went to the help desk of my university. A guy took a look (he also tried to plug an external screen) and said that the computer is dead: on the HP laptops eventually the GPU card dies and so does the motherboard because they are linked. He saw this many times, and even if I can fix the problem, the laptop would crash again after a while. Do you have similar experience with HP laptops ? (mine is 4 years old)

Edit 2: Believe it or not, my laptop is magically working again. I have no clue about what is going on. Now it is like starting and old car: when you turn it on you secretly hope it will actually start... With that said, I expect my laptop to break again in the near future (its an HP after all) and I will accept an answer or add my own accordingly.

Edit 3: As expected, the laptop is down again. This time, sometimes when I power it up, it shuts down automatically after 3 seconds, sometimes not at all. In addition, when it does not shut down on its own, the power button does not work : the only way to shut it down is by unplugging the battery. As before, the screen is black, and only the power and battery lights are on. (the other ones: hard drive and wifi are off). I have tried to plug in another power plug, removing the battery and removing the hard drive without success. I might buy another laptop.

I've brought the laptop to a repair shop. The problem is indeed that the graphic card is down. It will be replaced by a new one.