Uninstalling the Xen Virtualization package on CentOS can lead to an unexpected result. If no non-virtualized kernel was selected when the system was originally installed, you may be unable to boot!

To fix this, you need to install a kernel from the CentOS media:

Boot from the CentOS DVD

At the prompt type “linux rescue”

chroot /mnt/sysimage

Find the kernel you want to install on the DVD (or CD), and run “rpm -ivh kernel-[number].rpm

Reboot and you should be off and running!