Well, the saga continues.  It doesn't have much practical significance, but 
its an intellectual challenge, and its driving me crazy!
I have these three Compaqs.  They are just about identical.  They are all 
PIIIs, though two have 128Mb and the other 192.  That's the only difference.
I installed mandriva 2006 on all three in the same way, using the same boot 
disk and installing over the net from the same site.
Two of them are sitting next to each other on a table, connected to identical 
monitors.  I have removed the battery on both to reset the bios (necessary to 
remove password to do the install).  I've checked all the settings, and they 
are all set the same in bios.  The only change I made to defaults was to set 
the time.  I've checked that the ethernet chipset is the same, and it is.
On one, the network goes off at keyboard power off, and comes back on at power 
up from the base unit power switch.
On the other, everything reports fine at startup, but the little light on the 
built in ethernet port never comes on, and the network is first unavailable, 
then if you do ifdown eth0 followed by ifup eth0, it shows host unreachable.  
The light remains off.  Then if you do a soft power down, disconnect the 
power, reconnect the power, the light comes on, boot then causes it to give 
you the identical messages at startup, but this time it works.
Well, today, on the third one, which also does this, I put in a different pci 
ethernet card.  It worked perfectly.  Set it up as eth1, removed the other 
ethernet, eth0.  Soft off, it goes off, restart, it comes back on.  The only 
slight oddity was that it seemed very slow indeed in both printing and 
accessing the printer's web page.  It took several minutes to spool a one 
page document with a couple of screenshots on, and displaying the printers 
web page was rather slower than I would have expected over a 100mbps LAN 
connection.  But it worked on the problematic power aspect exactly as it 
should.
I had the vain hope that maybe it could be something to do with manual 
addressing, so took in a router and set one of the ones that doesn't work to 
DCHP, but of course this didn't help.  Its before that stage that the 
ethernet is failing to come up.
Of course, I can just put in a second extra ethernet card in the one that 
doesn't work, and probably will have to, but its driving me nuts.  This 
should not be possible.  Or if it is, there should be some explanation of 
what is different about the one that works.  I guess I can swap the hard 
drive of the one that works with one that doesn't and see if that makes a 
difference.  I could try installing Debian on another hard drive, and see if 
that makes any difference.  
I just do not want to be intellectually defeated by this!
Any other ideas?   Any ideas about anything else one could do to narrow down 
the problem?
Peter