CentOS hangs on startup after yum update

Usually it will hang after Starting certmonger: [OK]

Startup the hanging machine (H1)
From another machine do:

> ssh H1
> su
> mv /etc/X11/xorg.conf /etc/X11/xorg.conf.bak

Now restart H1.

You can have more explanations by doing a “tail -n 200 /var/logXorg.0.log” on the hanging machine.