dovecot - May 2015 - Googling: dovecot: auth-worker(default): pam_start() failed: Critical error - immediate abort

Howdy, Googling:

dovecot: auth-worker(default): pam_start() failed: Critical error - immediate
abort
dobbeltganger dovecot: auth-worker(default): pam(user,1.2.3.4): lookup
service=dovecot
dobbeltganger out of memory [4543]

returns just 3 references.

Examining memory server side reveals use of virtual memory but not 100%

OS: Ubuntu 14.04 client 10.04 server-side.
Email client: Thunderbird (Thunderbird prompts for the password which has worked
for years).

dovecot -n

# 1.2.9: /etc/dovecot/dovecot.conf
# OS: Linux 2.6.34.1-rscloud x86_64 Ubuntu 10.04.4 LTS 
log_timestamp: %Y-%m-%d %H:%M:%S 
ssl: required
verbose_ssl: yes
login_dir: /var/run/dovecot/login
login_executable: /usr/lib/dovecot/imap-logina
login_processes_count: 5
login_max_processes_count: 256
mail_max_userip_connections: 40
mail_privileged_group: mail
mail_location: maildir:~/Maildir
mail_debug: yes
mbox_write_locks: fcntl dotlock
auth default:
  realms: davidwbrown.name, karlbrown.name
  default_realm: dobbeltganger.com
  username_format: %n
  verbose: yes
  debug: yes
  debug_passwords: yes
  passdb:
    driver: pam
  userdb:
    driver: passwd
  socket:
    type: listen
    client:
      path: /var/spool/postfix/private/auth
      mode: 432
      user: postfix
      group: postfix