I am using a G4 500 Mhz Powerbook, and have notice of late, the fan turning on much more often that before. I have had the PB since Oct. 2001 and until recently the fan only came on if I was doing some serious processing, for extended periods of time(iTunes w/ visuals, DVD player, and such). But now just doing the regular stuff (4D in Classic, IE 5.1) the fan comes on almost once an hour. This Powerbook is my primary computer at work, so I use it about 9 hours a day. I use it in an air-conditioned home-office. I haven't noticed an increase in the environmental tempature. I am currently running OS 10.1.3 as my default OS, and I think it was shortly after the latest update that I started noticing the fan comming on more often. Is this something to worry about, or is this normal?