If you get an Encryption error on the login by using a root then try the following.
Login as root in the shell/ssh
1. try setting a new password for the root user.
passwd
if this does't help then try
2. Check hashing (hashing needs to be md5 or )
authconfig --test | grep hashing
if you get the following "password hashing algorithm is descrypt" then you need to change hashing type.
authconfig --passalgo=md5 --update
then again set the new root password
passwd