Many times you might have faced this problem.With Ubuntu live CD or fresh installation there is additional drives installer which runs in background.
You get the error as ‘Could not get lock /var/lib/dpkg/lock ‘ .The simple solution to this is to kill that background process.The process responsible for locking is jockey(‘additional drivers’).
killall jockey-gtk (for ubuntu)
killall jockey-kde (for kubuntu)
Thats all.Now open your synaptic/software-manager to install packages.