Tente
sudo rm -rf /var/lib/apt/lists/*
Então
sudo apt-get update
Err http://ppa.launchpad.net trusty/main i386 Packages
404 Not Found
Translation-en_IN
Ign http://packages.linuxmint.com rebecca/upstream Translation-en
Fetched 284 kB in 11s (23.9 kB/s)
Reading package lists... Done
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://extra.linuxmint.com rebecca Release: The following signatures were invalid: BADSIG 3EE67F3D0FF405B2 Clement Lefebvre (Linux Mint Package Repository v1) <[email protected]>
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/trusty/Release Unable to find expected entry 'restricted/binary-amd64/Packages' in Release file (Wrong sources.list entry or malformed file)
W: Failed to fetch http://packages.linuxmint.com/dists/rebecca/main/binary-i386/Packages Hash Sum mismatch
W: Failed to fetch http://ppa.launchpad.net/chris-lea/munin-plugins/ubuntu/dists/trusty/main/source/Sources 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/chris-lea/munin-plugins/ubuntu/dists/trusty/main/binary-amd64/Packages 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/chris-lea/munin-plugins/ubuntu/dists/trusty/main/binary-i386/Packages 404 Not Found
W: Some index files failed to download. They have been ignored, or old ones used instead.