Thank you very much ! I looked on the menu.lst but couldn't find anything
wrong, Ubuntu was also listed there but just could not be booted. I booted
Macpup Foxy and deleted GRUB from the Ubuntu partition but this did not solve
the problem and then unplugged the IDE hard disk to work on the SATA one, booted
the Ubuntu live CD and restored GRUB according to the instructions on the
Internet but this did not solve the problem either, Kanotix's GRUB loaded, with
Ubuntu in the boot menu but with the same error when trying to load it. As I was
desperate, I booted from the Kubuntu live CD, started the installer, resized the
Kanotix partition and installed Kubuntu. Its GRUB now loads Kubuntu, Kanotix or
Ubuntu with no trouble. It seems that there is really something wrong with
Kanotix's installer. Now I have a three-boot system on the giant SATA drive,
with Ubuntu and Kanotix on two huge partitions and Kubuntu on a smaller one and,
independently, another
three-boot system on the IDE drive, with gOS, Linux Mint (on most of the space)
and Macpup Foxy frugal. I did not really want this, but at least I have six
options.
I might seem to be an undecided maniac.