I’m having a similar issue as in the fellow with a newer version of Ubuntu was having in this threadhttp://linuxforums.org.uk/index.php?topic=11545.0. I tried the solution people gave in that thread (sudo apt-get update) and the symbol went away briefly. It came back. When I do run the update command in terminal I see many failed lines (see below) but not sure what in my software sources I should change. Help is appreciated.
Err http://archive.ubuntu.com quantal/main Sources
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal/restricted Sources
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal/universe Sources
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal/multiverse Sources
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal/main i386 Packages
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal/restricted i386 Packages
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal/universe i386 Packages
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal/multiverse i386 Packages
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal-updates/main Sources
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal-updates/restricted Sources
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal-updates/universe Sources
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal-updates/multiverse Sources
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal-updates/main i386 Packages
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal-updates/restricted i386 Packages
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal-updates/universe i386 Packages
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal-updates/multiverse i386 Packages
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal-security/main Sources
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal-security/restricted Sources
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal-security/universe Sources
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal-security/multiverse Sources
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal-security/main i386 Packages
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal-security/restricted i386 Packages
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal-security/universe i386 Packages
404 Not Found [IP: 91.189.91.15 80]
Err http://archive.ubuntu.com quantal-security/multiverse i386 Packages
404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal/main/source/Sources 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal/restricted/source/Sources 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal/universe/source/Sources 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal/multiverse/source/Sources 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal/main/binary-i386/Packages 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal/restricted/binary-i386/Packages 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal/universe/binary-i386/Packages 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal/multiverse/binary-i386/Packages 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-updates/main/source/Sources 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-updates/restricted/source/Sources 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-updates/universe/source/Sources 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-updates/multiverse/source/Sources 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-updates/main/binary-i386/Packages 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-updates/restricted/binary-i386/Packages 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-updates/universe/binary-i386/Packages 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-updates/multiverse/binary-i386/Packages 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-backports/main/source/Sources 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-backports/restricted/source/Sources 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-backports/universe/source/Sources 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-backports/multiverse/source/Sources 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-backports/main/binary-i386/Packages 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-backports/restricted/binary-i386/Packages 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-backports/universe/binary-i386/Packages 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-backports/multiverse/binary-i386/Packages 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-security/main/source/Sources 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-security/restricted/source/Sources 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-security/universe/source/Sources 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-security/multiverse/source/Sources 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-security/main/binary-i386/Packages 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-security/restricted/binary-i386/Packages 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-security/universe/binary-i386/Packages 404 Not Found [IP: 91.189.91.15 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/quantal-security/multiverse/binary-i386/Packages 404 Not Found [IP: 91.189.91.15 80]
E: Some index files failed to download. They have been ignored, or old ones used instead.