Yeah so this happened for the first time a few days ago. Just browsing the net and it completely shut off. At first I was worried but then it didnt happen for another day or so. Then programs were quitting unexpectedly, mainly safari. So this made me think maybe one of my 1gb ram sticks was bad. I ran memtest and and my macbook shut down, then i booted it up again and ran memtest for a second time and again it cut off. I tried a third time but this time it ran the all the tests and passed them all and my mac seemed to be back to normal for over a day....until today when it started to cut off again. I took out the ram modules one at a time and I thought this had done the trick until a little while ago when the power went. So it doesnt seem to be a problem with my ram. Any ideas what could be wrong? Any fixes? It only happens maybe once a twice a day but when you do alot of music work this really isnt good! Also it happens when the power supply is both in and out. I REALLY hope it's not screwed cos I love this thing. Thanks!