The other day a reader asked me that she had troubles with this kind of error:
E: Could not get lock /var/cache/apt/archives/lock – open (11: Resource temporarily unavailable)
E: Unable to lock directory /var/cache/apt/archives/
She was trying to follow one of the tips mentioned in things to do to after installing Ubuntu 14.04 when she encountered this error. Its one of the common occurring update errors in Ubuntu and also one of the least annoying ones.