Macbook Pro startup issues

[bravokilo]

Hey guys, recently I've been having a very annoying issues with my pre-unibody 2008 macbook pro. When I go to start it, either from sleep or completely off, it refuses to turn on. If I press the power button, the light on the latch will come on for a few seconds, the computer will try to start, then turn completely off, and the screen doesn't change from black at all. All of this happens in less than three seconds. If i hold the power button, the latch light will come on, flicker for a few seconds, then grow bright and dim, but ultimately turn off. The weird thing is, if I hold down the power button, press a bunch of random keys on the right side of the keyboard, then release the power button while the latch key is flickering, theres a about a 1 in 5 chance it will startup like normal. I've tried resetting SMC, and PRAM. Its not a battery issue, because it does this with full charge or on AC power. Could it be linked to the Nvidia graphics problem? I think I'm out of the 4 year since buying free fix period. Any sugguestions? Thanks.