I have found an easy way to fix this problem on the following webpage : http://forums.debian.net/viewtopic.php?p=85884&sid=253f85fa345866026fbf582e1c54e2b3
Basically you just need to change every 'sda' to 'hda' in your /etc/fstab file, and also in the entries for the new kernel in your /boot/grub/menu.lst (I just changed the root=hda1 into root=sda1 in mine and it works, I didn't change the 'root(hd0,0)' line). I have not changed the cdrom device as it is said on the forum, and I have no problem using it. Cheers! Matthieu
