Gnome Desktop Blank Screen (spinner never goes away)

UPDATE:  The root cause of this issue was that GDM AutomaticLogin was enabled in /etc/gdm/custom.conf but the login account had an expired password.  The problem went away when this was resolved.

Using the Cloudera CDH Quickstart VM 5.1 converted to a VMware template and running on ESXi 5.5, I was frequently getting a never ending spinner on the console to the graphical desktop (so basically, there was a blank black screen with the spinning "beachball").  It wasn't totally repeatable but it was happening more than half the time.  The VM uses Centos 6.5 under the hood.  

The fix was to kill the gnome gdm-simple-slave process, which then automatically restarts.  This would cause the console to flash and then the desktop would come up.  This command will do it:

pkill -o -f gdm-simple-slave

You can either ssh directly into the machine to run this, or do a Ctrl-Alt-F6 to switch the console to a command line and run it.

I'm not sure what the underlying problem is that's causing this but at least this can get past it.