Comment 9 for bug 316872

I have the same problem today when I tried to migrate to ext4.

1. Up-to date jaunty with new grub
2. Used jaunty alpha 3 liveCD to convert partition
3. Via live-cd:
  tune2fs -O extents,uninit_bg,dir_index /dev/sda1
  fsck -pf /dev/sda1
  mount -t ext4 /dev/sda1 /disk
  vi etc/fstab (ext3 -> ext4)
  vi boot/grub/menu.lst (add rootfstype=ext4)
4. Reboot
5. Observing a grub prompt
6. grub>setup (hd0) doesn't help

I have only one partitions for boot, root and home.