[CentOS] Kernel Panic post kernel-2.6.32-504.23.4.el6.x86_64

Greetings,

Today, I decided to reboot one of my CentOS machines after it had been 
running for 219 days.

In this time, I had done yum updates several times. When I tried rebooting 
the machine, none of the kernels would work except for the oldest one.

Here are the installed kernels:

kernel-2.6.32-504.23.4.el6.x86_64
kernel-2.6.32-573.3.1.el6.x86_64
kernel-2.6.32-573.7.1.el6.x86_64
kernel-2.6.32-573.8.1.el6.x86_64
kernel-2.6.32-573.12.1.el6.x86_64

Here is a uname -a:
Linux onavenuea 2.6.32-504.23.4.el6.x86_64 #1 SMP Tue Jun 9 20:57:37 UTC 
2015 x86_64 x86_64 x86_64 GNU/Linux

The CPU is a Intel Core 2 @2400 GHz; there is 6GB of RAM.

Much thanks for any advice in this regard.

Max Pyziur
pyz at brama.com