Upgraded to OSX Lion. Everything went smooth, didn't have any problems yet. Normally at night, I leave my computer running (ie: never shut it off, doesn't go to sleep, just keeps running). It runs for weeks at a time before a restart, never had a problem on 10.5 or 10.6. So, last night I leave it running like normal. It's the first time the machine hasn't been used for more than 3 hours in the day. I wake up early around 5am to a loud whirring noise. Go to the computer, the fan was running at max speed! I turned off the computer, everything was cool inside to the touch (HD, ram, GPU, etc). Nothing seemed out of the ordinary, but, this isn't something I'm wanting to happen again. Only posting to see if anyone else has had temp issues or glitches regarding fan speeds.