I had a major crash on my computer and afterward neither XP nor Linux
could start, after reinstalling XP I discovered that my bios settings
was wrong hyper-threading was now disabled, after reenabling it, I
tried to reinstall lilo using the following procedure:

boot cd (for rescue purposes), log in
mount /dev/whatever /mnt
mount -o bind /proc /mnt/proc
mount -o bind /dev /mnt/dev
chroot /mnt /bin/bash

(replace /dev/whatever with your correct device/partition)

Now I got the following message when trying to start

VFS: Can't find ext3 filesystem on dev ide0(3,3)
mount: Invalid argument.

This should be hda4???

(partioned as hda: hda1 hda2 < hda5 hda6 > hda3 hda4)

hda4 should be my linux partition.

e2fsck -f /dev/hda4

doesn't report any errors.

What can I do to bring it to life again?