https://discussions.apple.com/thread/2204669?start=0&tstart=0 Thanks kurmud for great info. My followup to your points are: 1. I do leave my computer on all the time, but I only use during the day a few hours. And, yes, I have a louder hard drive than my sons Powerbook. Nevertheless, it is clearly doing something more than a casual update as disk chatter is intense and long enough as if it was d..