HP Laptop Screen Display problem

I am having a weird version of this pretty well known problem. This is an HP Pavillion DV9520 laptop running Vista (it is not part of the recall from HP - but maybe it should be). From power-on, the screen is dead, absolute black. No HP, BIOS screen or the like. However, the machine is booting, the disks start and if I attach an external monitor the whole proper boot sequence can be seen (HP welcome screen, Vista login, Vista desktop). I have tried all the known fixes for this including reseating RAM, removing battery and holding power switch for 60 seconds, etc. I even tried popping out the backup battery. All to no avail.

I have found something that works fairly consistantly. If I attach an external monitor and leave the laptop lid open at about 30 degrees, the laptop screen works. I see the Microsoft moving bars on the laptop. However, when the Vista login screen comes up, the laptop goes dark and the external monitor (only) displays the Vista login screen. Once I enter my password (without lifting the lid from its 30 degree position) the laptop screen comes back on and I see the desktop on both screens.

I have not tried holding my mouth a certain way when I boot or getting up and walking around my chair twice but am willing to try if anyone thinks that will work. I would really appreciate any other ideas you have as well.

/sch
shamrinAsked:
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antontolentinoCommented:
Internal vga seem not properly connected.

you need to request to service it from HP
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dude02Commented:
 
When you have the secondary monitor hook up to the laptop go ahead and give this a try. Try to decrease the video settings by decreasing the resolution and color. I would check this to see if it is a video memory card problem.  
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antontolentinoCommented:
Double check if your display is configured to have a secondary screen. If yes, disable it.

This might happen if you accidentaly set a secondary display as primary and force tv detection is active.

it will always throw your display on a secondary display which is not attached.

That's why you are having display when you attach a secondary display.

It's just a possibility that you can look at.

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shamrinAuthor Commented:
I lowered the screen resolution and colour while both the monitor and laptop screen were working. Upon lowering the colour to 16-bit, the laptop screen went black (light glow but no data). I had to push the big orange switch to shut down. Upon rebooting, same black laptop problem. When I go into the NVIDIA Control Panel, I see that it does not recognise that there is a laptop screen attached, it only recognises the external monitor (even when doing a "Rigorous Detection").

/sch
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dude02Commented:
In that case the Video card seems to be working OK. Have you tried to re-install the video driver and chipset drivers for the laptop? I would give that a try just to make sure...
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shamrinAuthor Commented:
OK, here is one more datapoint.

The external monitor I am using is on a KVM switch. Just now, with both the laptop screen and external monitor screen showing the desktop, I flipped the KVM. When I did this, the laptop beeped twice (like a device had been disconnected) and the laptop screen went black. When I switch the KVM back to the laptop, both screens remain black and cannot be revived. I notice that the external monitor is getting a signal (because it doesn't go into sleep mode) but the signal is black. Ouch, I think my brain just hemmoraged.

/sch
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dude02Commented:
I would have to say you have to call HP. It looks like you either have a bad video display or something is going out on the motherboard.
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