[CentOS] Kernel panic after update to 6.4

After successfully updating three CentOS 6.3 VM guests to 6.4 I decided to update the host as well.  And it failed to boot.

Kernel panic - Not syncing: Attempted to kill init!
Pid: 1, comm: init not tainted: 2.6.32-358.2.1.el6.x86_64 #1
Plus a call trace I couldn't see

Luckily I was able to boot from the previous kernel and get my system back up.  After booting to the previous kernel I removed the "358" kernel and all of it's related module and devel packages using yum remove, then did yum update again, as I could only guess that the install somehow didn't complete.  But it still fails to boot.

Now the kernel panic has happened to a 6.3 VM guest I upgraded, now it isn't just the host hardware that is a problem.

Has anyone else seen this?

Any ideas where to start troubleshooting?

Emmett