About a month ago I noticed that my fan didn't stop spinning on my 07 Macbook for a long time, even when no applications were open. A restart always seemed to stop the issue, but after a while, and some CPU usage, the fan would just start back up again, non-stop. I started paying more and more attention to the Activity Monitor and noticed that even while I was doing nothing (every user application closed), User CPU % would be around 50%. I have no printer, so no open print jobs would be running. I reset my SMC controls periodically, but I just can't understand what would be forcing my computer to work so hard while I'm literally doing nothing. Even as I write this post, I can see that if I sort by CPU usage, only Activity Monitor and Safari are active, but in the stats section, it's constantly 40%-50% used. Does anybody know what is going on?