When I go to System Settings and click on Software Sources nothing happens. When I try
sudo apt-get dist-upgrade Reading package lists... Done Building dependency tree Reading state information... Done Calculating upgrade... Failed The following packages have unmet dependencies: gnome-shell : Depends: libcogl5 (>= 1.7.4) but it is not going to be installed Depends: gnome-shell-common (= 126.96.36.199-0ubuntu0.1) but 3.4.0+git20120401.c16dbd76-0ubuntu1~11.10~ricotz0 is to be installed gnome-shell-common : Breaks: gnome-tweak-tool (< 3.3) but 3.2.0-2ubuntu1~oneiric is to be installed libmutter0 : Breaks: gnome-shell (< 3.3.92~) but 188.8.131.52-0ubuntu0.1 is to be installed mutter-common : Breaks: gnome-shell (< 3.3.92~) but 184.108.40.206-0ubuntu0.1 is to be installed E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.