MacBook Pro Randomly Powering off

[sanclemente]

I'm hoping for some kind of insight on a phantom random shut off issue I'm having. I have a 2007 2.2ghz MacBook Pro running Snow Leopard and upgraded to 4GB ram. Within the last month, it has started to randomly power off. At first it only happened when I closed the lid and it went into sleep, but when I would arrive at school it would have shutdown on the trip. In the middle of this, I also replaced the battery. The day I put the new battery in, the thing freaked out. It powered off randomly while I was working. I was in the middle of the first battery calibration so I thought it might be a battery issue. When I tried to power back on, it would start to load the desktop and then power off again. I couldn't get it through a full boot cycle. I tried various configs of old battery, new battery, with power, without power cord and nothing seemed to work. Reset the SMC and PRAM as well to no avail. The longer I let it sit the longer I could work prior to power failure. So I assumed it was FUBAR and walked away.

Next morning called apple care and of course, things seemed fine. However, 1.5hours in, shuts off. Crap, Apple Care said go to Genius bar get it checked. Three days at Genius bar, full hardware and stress test and everything passed flying colors. I thought maybe it was a naughty little gnome who had decided to move on and torment some other guy. 3 days go by no problem, then today during sleep it powered off again. Then tonight, twice while working with powercord attached (one time losing about an hours worth of Excel work, which was a nice bonus).

Since everything checked out fine, I'm struggling with what to tell Apple if I take it back for repair. I need the laptop, but trying to work expecting impending doom when it randomly decides to shutdown sucks. I have apple care, but if they can't find any issues then it doesn't do me any good.
Any suggestions? Is it worth trying to do a clean install or look at some kind of software issue? Has anyone else dealt with this kind of issue? Please help.

 

[sanclemente]

Update

Well, after two separate trips to the apple store, and extended time without the computer as it went back to the repair depot, the computer is back and seems ok. Replaced the logic board and the problem is gone. Switching out the logic board FUBAR'd some of the software (namely VMWare Fusion) but after some google searches I was able to work all that out. Thanks for all the suggestions from everybody! Oh Wait....there weren't any.

 

[moole]

Same here

Same here. Macbook Pro 2007, 2.2 Ghz, randomly powering off in any combination of battery/power adapter/load/idle. Sometimes not even finishes booting, sometimes just hdd restarts (clicking noise). It started about month ago after I changed the original battery with the new one. I initially thought it's the battery, however, it then did it even with power plugged in and even without battery. It seems it's not connected with anything (load, heat, hdd activity, bending), it just does it sometimes.
Also my mainboard has been changed about half a year ago (3/2010) because of the nvidia problem. Since then the AHT (run once) indicated a "4SNS/1/40000000: TG0D" error, but i did not pay attention to it since nothing seemed to be wrong.
I hope, if it is an internal issue, that it is caused by the power board or something cheaper than mainboard as I have no apple care and the warranty is gone for long.