General :: Windows 7 - HP Laptop, Corrupted Graphics, Not Booting Win System Board?

My friend has a HP Pavilion dv2699ea (dv2500 series - somehow *shrugs*) that has stopped working. It's a Core2Duo laptop with a Nvidia GPU. The unit is no longer under warranty. Problems first started a few days ago with the laptop showing corrupted graphics in Windows and BSOD'ing after a few minutes of use. I tried booting to an Ubuntu LiveCD which worked for a while before succuming and crashing as well. The freezing/graphics corruption/BSODing does seem somewhat heat related (CPU runs at ~95'c under load) however I believe that if it is heat related, then it's already damaged components inside.

Now the system has corrupted graphics on bootup[1], including booting Ubuntu[2], and neither operating systems will boot at all (Windows can sometimes get logged in before showing a black screen and becoming unresponsive. Ubuntu just looks like [3] after X starts). (See comment below for links.)

The fact the problem occurs both under Linux and Windows says to me this is not a driver issue. I have run Memtest which passed fine and none of this seems HDD related as I managed to get ~30GB of data off the system before it finally gave up the ghost.

She has been using it repeatedly without giving it adequate ventilation for years (i.e. on the bed, or on a pillow), so it's my opinion that the system board has probably warped over years of cooling/heating and that's causing this current problem. If that is the case, then I can buy a replacement system board and fit it myself, saving about £200 over the cost of an out-of-warranty HP repair. Of course, I don't want to make her spend £100 on a replacement part for it to be the wrong thing, hence asking for a second opinion here!

Hopefully I've covered all the bases here. I'm a former IT support guy myself, so I've tried all the dumb stuff (driver updates, examining memory dumps from BSODs [one 'unrecoverable hardware error', three relating to the graphics card], etc).