What did I do since my last post ? As Richard suggested, I opened up
the box and checked cables around the cdrom hardware. I noticed
something that I thought weird at first: the CDROM blocks were
connected to a cable where one could read: "HD cable", while the HD
was linked to a cable that read "CDROM cable". I then swaped cables,
and tested. The only difference I got was that my Linux system now had
to be booted on /dev/hdc3, while it did boot on /dev/hda3 before.
Still, none of my CDs did operate on Debian, one did operate on MSWIN,
none would boot an autoboot system CD.
This being done, I decided to unplug one of my two CDROM drives, the
one that did not work on either system. I removed all cables from that
drive. This helped a lot, so it seems. My Debian system still boots on
/dev/hdc3, but now my only CDROM drive does work on /dev/hda (hda as
is, not on hda1 or whatever, which I did find weird though). It does
work, and also I am now able to boot on a system CD !! So, I could
possibly decide to re-install... I could also decide to use my machine
"as is" since it now operates almost as it did before, with only one
CDROM and no CD writer (but I don't need that on this particular
machine) ; I just changed the /boot/grub/menu.lst and replaced
"/dev/sda3 by "/dev/hdc3".
However... Something still has to be wrong with this machine. Why does
it now reckognises my HD and CD drives as /dev/hdc (hdc1 for MSWIN,
hdc2 for swap space and hdc3 for Debian system) and /dev/hda for the
now unique CDROM drive.... while it previously did reckognise these
pieces of hardware as SCSI drives (/dev/sda1, sda2, sda3 for the HD...
Nothing shows if I type:
Thanks in advance for you explanations and advices.