See the containers ' status.
# lxc-list RUNNING FROZEN STOPPED squeezie
Link the container's config file to /etc/lxc/auto so it starts at boot time.
# ln -s /var/lib/lxc/squeezie/config /etc/lxc/auto/squeeziesqueezie is the name of the container.
Test if you can afford to reboot the host.
# reboot
...
# lxc-list RUNNING squeezie (auto) FROZEN STOPPED
start a LinuX Container at boot