I have installed Xen 3.1.2 perfectly, and it's running fine. However since that version is way outdated I just updated it to 4.1.2 by adding the gitco repository and then yum update. It installed fine, modified my grub.conf to reflect the changes but then on a reboot, it simply doesn't come back online (I can't see what's going on, as it's a rented dedicated server).

What are my options? Booting into rescue mode and using the older kernel works fine, it will come back up. But once I use the xen.gz-4.1.2kernel, it won't come back up anymore and I need to use the rescue image..

My /boot/grub/grub.confis as follows:

title CentOS (2.6.18-308.1.1.el5xen)
        root (hd0,1)
        #kernel /xen.gz-2.6.18-308.1.1.el5 dom0_mem=1024M
        kernel /xen.gz-4.1.2
        module /vmlinuz-2.6.18-308.1.1.el5xen ro root=/dev/md1
        module /initrd-2.6.18-308.1.1.el5xen.img

When I uncomment the 3.1.2 kernel, it works fine, but booting with the 4.1.2 kernel fails and I have no idea what's going on. Hence my question: what are my options?