I'm working on an HP DV6000. In my case, I believe the screen is going or the inverter is going out. The external monitor is fine. If you have a nvidia chipset, they have a recall on HP's for a graphics issue. Also is you notebook running too hot? I have to keep a notebook cooler under it to keep it at a safe temp.
If anyone reads this thread, please reply to mine too. I had the notebook torn down to replace a bad heatsink fan. The problem here may be that the notebook was over heated. That would mean I should get a new board since the graphics is built into the mainboard. I guess I'm in a "Help me" mode now. Dan