Its happened to me before. I just turn it on and the light turns green but then immediately switches to yellow and then turns off to red. But dude why did you buy a 40gb? my warranty had expired and so i called sony and got a brand new 60gb for only $150. I tried to find a way to back up the data but I failed. It looks like your gona have to start from scratch all over again. It just happened out of randomness. I was in the middle of a game of COD4 online and it just turns off! Then i couldnt turn it bak on