Powerbook 667mhz random restarts

hi there
maybe i should stop buying apple gear on the cheap, but i couldnt resist this one. Bought as untested and when i added ram it booted fine
Was working for nearly a week before problems started. I also added an airport card a couple of days before.
It seems to cold boot fine, but then after about 5 minutes it will go blank and the startup chime rings. It then gets stuck in a cycle of rebooting and rebooting never getting anywhere.
I decided to reinstall the OS, but it restarted halfway through and left me with a blank drive. I left it on the flashing question mark screen for about half an hour and it didnt repeat the problem.Perhaps accessing the hdd for a length of time causes it.. :-S
Of course when i went to install again from my tiger dvd it restarted half way through again.
Could this be a harddrive problem or am i looking at a logic board replacement?
ps, the ram was an official apple service part

sounds like the logic board went kaput.

The solution was even more random than i thought
It seemed to be ok if it wasnt accessing the hdd. Thought its either got a dead drive controller or it was overheating
I changed the harddrive and apart from a couple of hiccups it is fine! I have used it a few times now for half an hour at a time (due to battery more than anything) and its worked.
Just thought id follow this up in case anyone else was stumped by something similar. It was strange that a dying harddrive would cause a powerbook to randomly restart!

oragano said:

It was strange that a dying harddrive would cause a powerbook to randomly restart!

Click to expand...

It did that on my PC 0_o