tonight, the fan of my ibook 800 came on for the first time since i bought it last november. i usually leave it on all the time (uptime now about 2 months minus one reboot for 10.2.4). at first i thought my hard disk was having a head crash...the fan really sounds scary (i didn't even know the ibook has one). it's kind of a high pitched, pulsating noise. anyone else ever heard the fan of his ibook?