CentOS will not boot. Error 13

I am having trouble with one of our CentOS servers.

I migrated this server to XenServer, installed a new xen kernel, and performed a mkinitrd with:

mkinitrd --omit-scsi-modules --with=xennet --with=xenblk --preload=xenblk initrd-2.6.18-308.4.1.el5xen-no-scsi.img 2.6.18-308.4.1.el5xen

Now I am getting an error 13 on boot. Screenshot: http://postimage.org/image/k7js0l41v/

I can still boot with the PAE kernel. Does anyone have any idea on how to resolve this? My Grub file looks like:

default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title CentOS (2.6.18-308.4.1.el5xen)
    root (hd0,0)
    kernel /vmlinuz-2.6.18-308.4.1.el5xen ro root=/dev/hdb1 ramdisk_size=256000
    initrd /initrd-2.6.18-308.4.1.el5xen-no-scsi.img
title CentOS (2.6.18-308.4.1.el5PAE)
    root (hd0,0)
    kernel /vmlinuz-2.6.18-308.4.1.el5PAE ro root=/dev/hdb1 ramdisk_size=256000
    initrd /initrd-2.6.18-308.4.1.el5PAE.img
title CentOS (2.6.18-274.17.1.el5PAE)
    root (hd0,0)
    kernel /vmlinuz-2.6.18-274.17.1.el5PAE ro root=/dev/hdb1 ramdisk_size=256000
    initrd /initrd-2.6.18-274.17.1.el5PAE.img

I have figured out the cause of this issue and created a tutorial how to fix this for anyone else facing the same problem.

http://zconkle.blogspot.com/2012/04/xenserver-converting-centos-from-hvm-to.html

Check more discussion of this question.

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