Roberto, did you find a solution? I have EXACTLY the same problem you described. I'm think there's a driver that causes the system to shutdown after a while, but I also learned that shutdowns come from the first time I connect to the Internet... Could it be some update that windows is downloading what causes the system to shutdown? I also get like 5 minutes or so til system goes down, buy I'm pretty sure it doesn't have nothing to do with temperature, as shutdowns come unexpectedly and sometimes when the system is idle, so temperature monitor is in some cases reading temps of less than 60 C. Hope there's some sort of solution for our unlucky machines! Thanks for sharing!