Reading package lists... Done
Building dependency tree       
Reading state information... Done
You might want to run ‘apt-get -f install’ to correct these.
The following packages have unmet dependencies.
 network-manager : Breaks: ppp (< 2.4.6) but 2.4.5-5.1ubuntu2.2 is installed
                   Recommends: ppp (>= 2.4.6) but 2.4.5-5.1ubuntu2.2 is installed
 network-manager-pptp : Depends: ppp (>= 2.4.7-1+~) but 2.4.5-5.1ubuntu2.2 is installed
E: Unmet dependencies. Try using -f.