grub

When you install grub to debian and forget to run update-grub the first time before you reboot then there is no menu.lst file in /boot/grub so you boot to the grub shell

I had the following config

/dev/hda2 - /
/dev/hda3 - /boot

To boot this from the grub shell

root=(hda0,2)

This points to /boot (hd0 is /dev/hda - the number after the comma is zero indexed partition number - so ,2 is /dev/hda3)

kernel=/vmlinuz-... root=/dev/hda2 ro

Full details on

http://myrddin.org/howto/debian-grub.php

If you have LILO on the MBR then the grub-install device is the disk e.g. /dev/hda - not the root partition.