Ubuntu – Lightdm not starting at boot in Ubuntu 14.04

I've been reading lots of posts about this problem regarding previous versions of Ubuntu, but they don't seem to work in my case.

At boot and shown in /var/log/boot.log the daemon /usr/sbin/lightdm, simply shuts down – seemingly without any obvious error, leaving me stuck with the "Kubuntu" grinning at me. Then, if I fire up a terminal, log in and perform a "service lightdm start" it will start perfectly.

I've tried some "ugly hacks" to make it start up, such as adding a bottom line in the init-script "/etc/init.d/lightdm" service lightdm start or /etc/init.d/lightdm start, but still it will not start at boot. All other displaymanagers (gdm and kdm) are uninstalled.

Any ideas?

#!/bin/sh

# Largely adapted from xdm's init script:
# Copyright 1998-2002, 2004, 2005 Branden Robinson <branden@debian.org>.
# Copyright 2006 Eugene Konev <ejka@imfi.kspu.ru>
#
# This is free software; you may redistribute it and/or modify
# it under the terms of the GNU General Public License as
# published by the Free Software Foundation; either version 2,
# or (at your option) any later version.
#
# This is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License with
# the Debian operating system, in /usr/share/common-licenses/GPL;  if
# not, write to the Free Software Foundation, Inc., 51 Franklin Street, 
# Fifth Floor, Boston, MA 02110-1301, USA.

### BEGIN INIT INFO
# Provides:          lightdm
# Required-Start:    $local_fs $remote_fs
# Required-Stop:     $local_fs $remote_fs
# Should-Start:      $named acpid hal
# Should-Stop:       $named
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Start lightdm
### END INIT INFO

set -e

HEED_DEFAULT_DISPLAY_MANAGER=
# To start lightdm even if it is not the default display manager, change
# HEED_DEFAULT_DISPLAY_MANAGER to "false."
# Also overridable from command line like:
# HEED_DEFAULT_DISPLAY_MANAGER=false /etc/init.d/lightdm start
[ -z "$HEED_DEFAULT_DISPLAY_MANAGER" ] && HEED_DEFAULT_DISPLAY_MANAGER=true

DEFAULT_DISPLAY_MANAGER_FILE=/etc/X11/default-display-manager

PATH=/bin:/usr/bin:/sbin:/usr/sbin
DAEMON=/usr/sbin/lightdm
PIDFILE=/var/run/lightdm.pid

if [ -r /etc/default/locale ]; then
  . /etc/default/locale
  export LANG LANGUAGE
fi

test -x $DAEMON || exit 0

. /lib/lsb/init-functions

SSD_START_ARGS="--pidfile $PIDFILE --name $(basename $DAEMON) --startas $DAEMON -- -d"
SSD_STOP_ARGS="--pidfile $PIDFILE --name $(basename $DAEMON) --retry TERM/5/TERM/5"

case "$1" in
  start)
    if [ "$HEED_DEFAULT_DISPLAY_MANAGER" = "true" ] &&
       [ -e $DEFAULT_DISPLAY_MANAGER_FILE ] &&
       [ "$(cat $DEFAULT_DISPLAY_MANAGER_FILE)" != "/usr/bin/lightdm" -a "$(cat $DEFAULT_DISPLAY_MANAGER_FILE)" != "/usr/sbin/lightdm" ]; then
      echo "Not starting X display manager (lightdm); it is not the default" \
        "display manager."
    else
      log_daemon_msg "Starting X display manager" "lightdm"
      start-stop-daemon --start --quiet $SSD_START_ARGS \
        || log_progress_msg "already running"
      log_end_msg 0
    fi
  ;;

  restart)
    [ -f $PIDFILE ] && /etc/init.d/lightdm stop
    [ -f $PIDFILE ] && exit 1
    /etc/init.d/lightdm start
  ;;

  stop)
    log_daemon_msg "Stopping X display manager" "lightdm"
    if ! [ -f $PIDFILE ]; then
      log_progress_msg "not running ($PIDFILE not found)"
    else
      start-stop-daemon --stop --quiet $SSD_STOP_ARGS
      SSD_RES=$?
      if [ $SSD_RES -eq 1 ]; then
        log_progress_msg "not running"
      fi
      if [ $SSD_RES -eq 2 ]; then
        log_progress_msg "not responding to TERM signals"
      else
    if [ -f $PIDFILE ]; then
      log_progress_msg "(removing stale $PIDFILE)"
      rm $PIDFILE
    fi
      fi
    fi
    log_end_msg 0
  ;;
  force-reload)
    /etc/init.d/lightdm restart
  ;;

  *)
    echo "Usage: /etc/init.d/lightdm {start|stop|restart|force-reload}"
    exit 1
    ;;
esac
exit 0