Original post by: rdklinc ,
You might want to remove the extended RAM module and Airport, and reset the PMU and PRAM. This can sometimes make a difference. Beyond that, it's likely a flaky board, since bad hard drives rarely cause the computer to freeze up. Is the light on the AC adapter flickering or going between different colors by chance? Sometimes when the DC-in plug is bad it can be very sensitive, and a computer without working battery will die or freeze just from being bumped lightly. Good luck!