After problematic boot issues I believed the problem centered on the old 160 Gb original hd in this machine. I installed a Samsung 840 EVO SSD and extra RAM thinking some more life could be had with these upgrades. I then tried installing Mountain Lion, which after some difficulty finally installed.
Now, the MBP will sometimes:
- hang on boot up after the Apple appears and it starts cycling.
- restart on its own.
- get stuck in a boot loop.
- boot up only to eventually hang after a checkerboard glitch on the screen.
I'm thinking it's the logic board or the NVIDIA GeForce 8600M GT GPU.
Any thoughts on what might be causing this behavior?