Thanks Sam,
The issue has been resolved. I've moved my moodle directory to /var/www/html and it's fixed.
correct permission:
-rw-r--r-- 1 root root 1481 Feb 1 13:29 ntlmsso_attempt.php
-rw-r--r-- 1 root root 1269 Feb 1 13:29 ntlmsso_finish.php
-rw-r--r-- 1 root root 1468 Feb 1 13:29 ntlmsso_magic.php
Mike