I'm using my Macbook (see sig for specs). The fan, for several hours now, has been running fast (6100 rpm) with little to no usage. It started when I was running VM Ware Fusion. Understandable. It frequently does when I'm running that. However, it's been running just OS X for 2 hours now, and it hasn't slow down. I'm not running Firefox and iTunes. That's it. I tried to restart and initially my fan was slow and quiet again, but minutes later it's up to 6300 rpm. It says I'm using about 60% of my CPU. Nothing in the Activity Monitor looks overly suspicious. What's going on?