Sudden shutdown/freeze; cause unknown
I've got an 2 and a half year old MBP A1260 which suddenly shuts down for no obvious reason. I recently upgradet my RAM to 4GB but the MBP still shuts down with the old RAM. It sometimes works fine for many hours but sometimes it shuts down right after booting. I already cleaned everything up inside and renewed the heatsink paste on suspicion which was necessary but did not help. I checked every connector so I guess a loose connection isn't the reason either. The Apple hardware check didn't report any problems.
It might has to do with the motion sensor as it sometimes shuts down after moving the screen or lifting the MBP up but I don't know how to check that. If it rests at my desk nothing happens.
I'm quite helpless with this especially because I did not find anyone with the same problems/symptoms. I appreciate any help.
Is this a good question?