Ooooops, No authentication RH7.2

[Mark Street]

I upgraded another box to RH 7.2 lastnight and on reboot I was not able to
login to any of my accounts......even root.

I am able to boot into single and use the passwd facilities to update
passwords.  However on runlevel change to 3 or reboot I cannot login from
the login prompt.

I checked the logs and all I can garnish is an authentication error, no
specifics.  I took a peek at pam and it has changed a bit to different
modules and configuration.  I do have the upgrade.log but nothing stands
out as unusual.

This box is one of my long standing UPgraders, it has progressed from RH
5.0 > 7.2 through each upgrade.  Other than not being able to authenticate
the system is working fine. : |

Any ideas?