can't mount my root partition (rescue mode)

[kiehl@nerim.net]

Hi all,

I have a debian sid. I can't boot anymore with grub because of an error 24.

So I use a knoppix to rescue my Debian.

The problem is that I can't mount my root partition (which is /dev/hda4)

root@1[knoppix]# mount -t ext3 /dev/hda4 /mnt/hda4
mount: wrong fs type, bad option, bad superblock on /dev/hda4,
       missing codepage or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

Any idea why ? /dev/hda4 is however an ext3 filesystem...
The problem is the same if i try to mount hda5. However, I can mount hda1
and  hda2.

Some informations :
root@1[knoppix]# fdisk -l /dev/hda

Disque /dev/hda: 80.0 Go, 80026361856 octets
16 têtes, 63 secteurs/piste, 155061 cylindres
Unités = cylindres de 1008 * 512 = 516096 octets

Périphérique Amorce    Début         Fin      Blocs    Id  Système
/dev/hda1   *           1       21314    10742224+   7  HPFS/NTFS
/dev/hda2           21325       77520    28322595    c  W95 FAT32 (LBA)
/dev/hda3           77536      139187    31072608    f  W95 Etendu (LBA)
/dev/hda4          139188      155061     8000496   83  Linux
/dev/hda5           77537      138800    30876898+  83  Linux
/dev/hda6          138801      139187      195016+  82  Linux swap / Solaris

root@1[knoppix]# cat /etc/fstab
/proc      /proc       proc   defaults            0 0
/sys       /sys        sysfs  noauto              0 0
/dev/pts   /dev/pts    devpts mode=0622           0 0
/dev/fd0   /mnt/auto/floppy auto   user,noauto,exec,umask=000    0 0
/dev/cdrom /mnt/auto/cdrom  auto   user,noauto,exec,ro 0 0
# Added by KNOPPIX
/dev/hda1 /mnt/hda1 ntfs
noauto,users,exec,ro,umask=000,uid=knoppix,gid=knoppix 0 0
# Added by KNOPPIX
/dev/hda2 /mnt/hda2 vfat
noauto,users,exec,umask=000,uid=knoppix,gid=knoppix 0 0
# Added by KNOPPIX
/dev/hda4 /mnt/hda4 ext3 noauto,users,exec 0 0
# Added by KNOPPIX
/dev/hda5 /mnt/hda5 ext3 noauto,users,exec 0 0
# Added by KNOPPIX
/dev/hda6 none swap defaults 0 0

Thanks,

   Pascal