Strange system hang

[Tyler Braun <tyler@chimptrix.chimp.ca>]

I'm not entirely sure if this is a hardware, kernel, or operating system issue,
but I'm hoping somebody out there has some insight.

Twice over the past few months my hard drive has seemingly gone berserk. I have
a very loud drive, one that frequently wakes me up when running daily jobs every
morning at 6:30ish. (sidenote: if anyone knows how to change this time please
let me know, I've been trying for some time) Thus I'm quite sure this isn't the
result of any rogue cron jobs. 

These two incidents occured at different times of day, once about 10 minutes
after the daily cron jobs, roughly 6:40ish, the other around 10am.

Both times I've tried to get my monitor to power back on but the system doesn't 
respond for a number of minutes. (5-10) After this time the monitor does power
back on but nothings responding, and the disk continues to grind away. Each time
this has happened I became concerned my hardware was going to be damaged and
shut down the machine after 15-20 minutes. 

Thus far nothing's been damaged, and this happens very rarely. It's quite scary
none-the-less. The first incident was around 10am, and under a 2.2.x kernel. The
second was under a 2.4.x kernel, and occured at roughly 6:45, around 10 minutes
after my daily cron jobs. (which often cause alot of disk activity) 

I'd be very interested to hear from anybody who might have encountered something
similar. It could be standard operating system activity, but I picked up that
the sound the drive was making wasn't normal both times, and normally during
heavy disk activity jobs the system will respond, so I'm quite sure this is
something out of the ordinary. 

Thanks in advance for any help you can provide.

-- 
Tyler Braun
tyler@chimptrix.chimp.ca