I don’t doubt that you’re having trouble logging in, but I strongly doubt that using NTP services is the root cause.
In order to be able to say more about such a problem access to the log files would be helpful, especially /var/log/auth.log and /var/log/syslog. I know that you cannot log in at the moment which complicates matters, but you could boot the machine from a Linux rescue CD (e.g. GRML or the SystemRescueCD, mount the partitions (don’t forget to start the logical volume manager; »vgchange -a y« should activate all volumes if they haven’t been activated automatically) and access the files from there.
Looking at those log files may hopefully give you an insight into what’s wrong.
A couple of things to consider:
[ul][li]root is not stored in the LDAP but locally on the machine. Therefore even if the LDAP server is down you should always be able to log on the console as root (and alsmost always via SSH as root, too).[/li]
[li]If you cannot log in as root then please paste the content of the following files here: /etc/pam.d/login, /etc/pam.d/common-*[/li]
[li]Also make sure that /etc/passwd and /etc/shadow haven’t been correupted, that there are no two entries for root etc.[/li]
[li]You could try changeing the root password from the rescue CD. Make sure the root partition is mounted, then execute »chroot /mnt /bin/bash« followed by »passwd«. If this succeeds try rebooting the system normally and logging in with the new password. If it fails then the error message(s) might be of interest.[/li][/ul]