Problema de atualização do Linux mint

Question

Eu tenho um problema ao fazer atualizações. Se eu digitar sudo apt-get updates, recebo o seguinte:

Err http://ppa.launchpad.net saucy/main Sources                                                                                                                
404  Not Found
Err http://ppa.launchpad.net saucy/main amd64 Packages                                                                                                         
404  Not Found
Err http://ppa.launchpad.net saucy/main i386 Packages                                                                                                          
404  Not Found
Ign http://packages.linuxmint.com petra/main Translation-en                                                                                                    
Ign http://ppa.launchpad.net saucy/main Translation-en_US                                                                                                          
Ign http://packages.linuxmint.com petra/upstream Translation-en_US                                                                                             
Ign http://ppa.launchpad.net saucy/main Translation-en                                                                                                         
Ign http://ppa.launchpad.net saucy/main Translation-en_US                                                                                                      
Ign http://ppa.launchpad.net saucy/main Translation-en                                                                                                         
Ign http://ppa.launchpad.net saucy/main Translation-en_US                                                                                                      
Ign http://packages.linuxmint.com petra/upstream Translation-en                                                                                                
Ign http://ppa.launchpad.net saucy/main Translation-en                                                                                                         
Ign http://ppa.launchpad.net saucy/main Translation-en_US                                                                                                      
Ign http://ppa.launchpad.net saucy/main Translation-en                                                                                                         
Ign http://ppa.launchpad.net saucy/main Translation-en_US                                                                                                      
Ign http://ppa.launchpad.net saucy/main Translation-en                                                                                                         
Fetched 204 kB in 9s (21,7 kB/s)                                                                                                                               
W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/dists/saucy/main/binary-amd64/Packages  404  Not Found

W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/dists/saucy/main/binary-i386/Packages  404  Not Found

W: Failed to fetch http://ppa.launchpad.net/shnatsel/zram/ubuntu/dists/saucy/main/source/Sources  404  Not Found

W: Failed to fetch http://ppa.launchpad.net/shnatsel/zram/ubuntu/dists/saucy/main/binary-amd64/Packages  404  Not Found

W: Failed to fetch http://ppa.launchpad.net/shnatsel/zram/ubuntu/dists/saucy/main/binary-i386/Packages  404  Not Found

E: Some index files failed to download. They have been ignored, or old ones used instead.

A saída do inxi -r é:

Repos:     Active apt sources in file: /etc/apt/sources.list
       deb http://extras.ubuntu.com/ubuntu/dists/ saucy main
       Active apt sources in file: /etc/apt/sources.list.d/additional-repositories.list
       deb http://download.virtualbox.org/virtualbox/debian saucy contrib
       Active apt sources in file: /etc/apt/sources.list.d/chris-lea-node_js-saucy.list
       deb http://ppa.launchpad.net/chris-lea/node.js/ubuntu saucy main
       deb-src http://ppa.launchpad.net/chris-lea/node.js/ubuntu saucy main
       Active apt sources in file: /etc/apt/sources.list.d/fossfreedom-packagefixes-saucy.list
       deb http://ppa.launchpad.net/fossfreedom/packagefixes/ubuntu saucy main
       deb-src http://ppa.launchpad.net/fossfreedom/packagefixes/ubuntu saucy main
       Active apt sources in file: /etc/apt/sources.list.d/google-talkplugin.list
       deb http://dl.google.com/linux/talkplugin/deb/ stable main
       Active apt sources in file: /etc/apt/sources.list.d/no1wantdthisname-ppa-saucy.list
       deb http://ppa.launchpad.net/no1wantdthisname/ppa/ubuntu saucy main
       deb-src http://ppa.launchpad.net/no1wantdthisname/ppa/ubuntu saucy main
       Active apt sources in file: /etc/apt/sources.list.d/nviennot-tmate-saucy.list
       deb http://ppa.launchpad.net/nviennot/tmate/ubuntu saucy main
       deb-src http://ppa.launchpad.net/nviennot/tmate/ubuntu saucy main
       Active apt sources in file: /etc/apt/sources.list.d/official-package-repositories.list
       deb http://packages.linuxmint.com/ petra main upstream import
       deb http://archive.ubuntu.com/ubuntu/ saucy main restricted universe multiverse
       deb http://archive.ubuntu.com/ubuntu/ saucy-updates main restricted universe multiverse
       deb http://security.ubuntu.com/ubuntu/ saucy-security main restricted universe multiverse
       deb http://archive.canonical.com/ubuntu/ saucy partner
       Active apt sources in file: /etc/apt/sources.list.d/olivier-berten-misc-saucy.list
       deb http://ppa.launchpad.net/olivier-berten/misc/ubuntu saucy main
       deb-src http://ppa.launchpad.net/olivier-berten/misc/ubuntu saucy main
       Active apt sources in file: /etc/apt/sources.list.d/shnatsel-zram-saucy.list
       deb http://ppa.launchpad.net/shnatsel/zram/ubuntu saucy main
       deb-src http://ppa.launchpad.net/shnatsel/zram/ubuntu saucy main
       Active apt sources in file: /etc/apt/sources.list.d/ubuntu-wine-ppa-saucy.list
       deb http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu saucy main
       deb-src http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu saucy main
       Active apt sources in file: /etc/apt/sources.list.d/webupd8team-java-saucy.list
       deb http://ppa.launchpad.net/webupd8team/java/ubuntu saucy main
       deb-src http://ppa.launchpad.net/webupd8team/java/ubuntu saucy main
       Active apt sources in file: /etc/apt/sources.list.d/webupd8team-sublime-text-3-saucy.list
       deb http://ppa.launchpad.net/webupd8team/sublime-text-3/ubuntu saucy main
       deb-src http://ppa.launchpad.net/webupd8team/sublime-text-3/ubuntu saucy main
       Active apt sources in file: /etc/apt/sources.list.d/xorg-edgers-ppa-saucy.list
       deb http://ppa.launchpad.net/xorg-edgers/ppa/ubuntu saucy main
       deb-src http://ppa.launchpad.net/xorg-edgers/ppa/ubuntu saucy main

E minha sources.list contém apenas:

deb http://extras.ubuntu.com/ubuntu/dists/ saucy main