Dpkg fatal error
I found how to solve on the Ubuntu italian forum:
sudo rm /var/lib/dpkg/info/gnuplot-data*
sudo dpkg --remove --force-remove-reinstreq gnuplot-data
sudo apt-get update && sudo apt-get dist-upgrade
Source: http://forum.ubuntu-it.org/viewtopic.php?f=8&t=606310&p=4840071#p4840071