I have a Toshiba Satellite Pro L300 which I've been running Ubuntu on for several months now and it keeps overheating. This wasn't a problem I ever had when I was running Windows Vista. I can understand it overheating on my lap, but because of this problem I keep it sitting on a wooden chair propped up on books and yet it still overheats and shuts itself down. Any ideas on why and what I can do to fix it?