Comment 31 for bug 587426

I can confirm this fix works (Skip and gfarmerfr combined)

file: /etc/init.d/boinc-client
----
start()
{
  log_begin_msg "Starting $DESC: $NAME"
  if is_running; then
    log_progress_msg "already running"
  else
    xhost local:boinc
    sleep 5
    start-stop-daemon --start --quiet --background --pidfile $PIDFILE \
      --make-pidfile --user $BOINC_USER --chuid $BOINC_USER \
      --chdir $BOINC_DIR --exec $BOINC_CLIENT -- $BOINC_OPTS
  fi
  log_end_msg 0

----

I think a user always needs to be logged in for BOINC to gain access to xorg. Maybe not the best fix, but better than nothing.