CentOS - Apr 2008 - Odd behaviour with modules; looking for some theories

Hi all,
	Recently, after doing some maintenance on one of my servers
(Centos 5), I rebooted.  On reboot, it didn't find the SAN disks at all,
and after some poking around in maintenance mode, I discovered that it
couldn't find the Qlogic module.  It turns out that
/lib/modules/<kernel-version>/modules.alias, modules.dep and such were
all empty or just had their header comment lines.   moddep -a fixed
things up quickly enough once I figured out what was going on.

However, I'm kinda stumped as to how these files got nuked in the first
place.  It wasn't files being deleted completely, it's like they were
regenerated incorrectly.  Checking backups showed these files were last
changed (to their short form) on Feb 11; yum.log doesn't show any sign
of updates on that date, so presumably it wasn't something like a kernel
installation running amok.  

Does anyone have any theories as to what happened?   Random logical
guesses is fine ;-)

Thanks,

Craig Miskell,
Technical Support,
AgResearch Invermay
03 489-9279
"Usenet is like a herd of performing elephants with diarrhea -- 
massive, difficult to redirect, awe-inspiring, entertaining, and a
source of 
mind- boggling amounts of excrement when you least expect it." 
	-- Gene "spaf" Spafford (1992) 
======================================================================Attention:
The information contained in this message and/or attachments
from AgResearch Limited is intended only for the persons or entities
to which it is addressed and may contain confidential and/or privileged
material. Any review, retransmission, dissemination or other use of, or
taking of any action in reliance upon, this information by persons or
entities other than the intended recipients is prohibited by AgResearch
Limited. If you have received this message in error, please notify the
sender immediately.
=======================================================================