The package system is broken
Check if you are using third party repositories. If so disable them, since they are a common source of problems.
Furthermore run the following command in a Terminal: apt-get install -f
The following packages have unmet dependencies:
calibre: Depends: python (>= 2.6) but 2.7.3-0ubuntu2.2 is installed
Depends: python-pypdf (>= 1.10) but 1.13-1 is installed
Depends: python-cssutils (>= 0.9.6) but 0.9.8-1ubuntu2 is installed
Depends: python-encutils (>= 0.9.5) but it is a virtual package
Depends: python-cherrypy3 (>= 3.1.1) but 3.2.2-2 is installed
Depends: ttf-liberation but it is not installed
Depends: calibre-bin (>= 0.6.42+dfsg-0ubuntu1) but 0.8.38+dfsg-1 is installed
When i run - apt-get install -f in the Terminal i get:
E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied)
E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?