I'm back where I was yesterday, this time sans nvidia module.

Sound was working great for a while, but then it suddenly locked up when
  I started to create a bzfile from a tarball created on another machine.
  Things locked up hard, exactly like I reported in the previous cs4236
  thread.
On reboot, it locked up yet again when I tried to play sound.  This time,
  I noticed that (as I am certain was the case before), prelink was
  running.

Thus, we have, sans nvidia driver, a big coincidence.  We have hard
  lockups (no, MagicSysRq keys don't work; verified), and the second
  lockup results in data loss in /, depending on what was going on
  (prelink; takes out random binaries and libs and replaces the contents
  with a huge sequence of "^@").

I'm thinking it's possibly either:
  a) chance interaction of the aic7xxx driver and the cs4236 driver
     Higher the disk throughput with sound going, the higher the chance of
     failing.
   or
  b) chance SMP problem (is an SMP box).  Higher the load, the higher
     the chance of failing.
   or
  c) prempt.

It's interesting how the files got replaced by "\@" too.

Anyhow, the config and loaded module list is attached, for your perusal.

-Joseph
-- 
trelane@digitasaru.net--------------------------------------------------
"We continue to live in a world where all our know-how is locked into
 binary files in an unknown format. If our documents are our corporate
 memory, Microsoft still has us all condemned to Alzheimer's."
    --Simon Phipps, http://theregister.com/content/4/30410.html