Get this message after running Update Manager
.....is it an easy fix??
W:GPG error: http://www.bunkus.org ./ Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY BCCF7AF0B6571FCA, W:Failed to fetch http://mirror3.ubuntulinux.nl/dists/natty-seveas/freenx/source/Sources 404 Not Found
, W:Failed to fetch http://mirror3.ubuntulinux.nl/dists/natty-seveas/freenx/binary-i386/Packages 404 Not Found
, E:Some index files failed to download. They have been ignored, or old ones used instead.