can 't boot fedora 12 from usb HDD, after upgrade from fedora12 to fedora13 faild.
 

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root (hd0,1)
kernel /vmlinuz-2.6.32.16-141.fc12.x86_64 ro root=/dev/mapper/vg_usbzzg-lv_root 1
initd /initramfs-2.6.32.16-141.fc12.x86_64.img

find /boot/grub/stage1
(hd0,1)

lvdisplay
--- Logical volume ---
LV Name /dev/vg_usbzzg/lv_root
VG Name vg_usbzzg
LV UUID jnCYK1-t8DD-4Tel-TQ46-Yn3i-GmvK-lIPfna
LV Write Access read/write
LV Status NOT available
LV Size 77.91 GB
Current LE 19944
Segments 1
Allocation inherit
Read ahead sectors auto

--- Logical volume ---
LV Name /dev/vg_usbzzg/lv_swap
VG Name vg_usbzzg
LV UUID lIcmMj-5ptZ-r1gd-Whfl-eAZa-Bwj7-bDQjrJ
LV Write Access read/write
LV Status NOT available
LV Size 1.97 GB
Current LE 504
Segments 1
Allocation inherit
Read ahead sectors auto

ls /dev/mapper/
control vg_usbzzg-lv_root vg_usbzzg-lv_swap