My ps3 turns off by itself solution !!!

Hello, my 40GB PS3 turns off by itself after 5 minutes. I couldn't find a solution, so I disassembled and cleaned it, changed the fans, and still nothing. My dad told me to put it in a plastic bag and put it in the freezer for an hour. I tried it, and I was able to play for 2 hours!! Apparently, it's a sensor problem, and the temperature sensor is really expensive and hard to repair, so there you go... a little trick to be able to play for 2 hours ;) I promise it works!! It's the only solution...