md5sum & cmp don't work on wav & avi files

[Michael Waters <stonin@rogers.com>]

Hi,

I was stress testing an old P233 that I just got when I discovered that
md5sum, cmp, and cksum don't seem to work on particular wav & avi
files.  Does anyone know anything about this?  

If I use md5sum several times on the same particular file, I get
differing sums.  If I copy the file to a different drive or partition
and use cmp, cmp reports differences.

The file here exhibits this for me:
http://lame.sourceforge.net/download/samples/hihat.wav .

Am I going crazy or do I have bad hardware?  I can't seem to find any
info in search engines.  Any information would be greatly appreciated.

Thank you,
Michael