Dan Reed writes:
 > I lost net connection and when I went to the iBook I HEARD the hard drive
 > knocking!  It sounded like the head was just slamming around in there...it
 > was definately not normal disk activity.  Anyway, luckily there was some
 > info in messages after I rebooted:

Yikes!  Look at all those bit errors in the log.  Since you
mentioned horrible sounds coming from the drive it's probably the
drive that's failing, but it's possible that the disk controller
is at fault.