how can I solved this "Err http://ppa.launchpad.net oneiric/main Sources "

[hoboy]

I have tried to solve this problem wihtout succes.
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Hit http://archive.ubuntu.com oneiric-security/universe Translation-en
Err http://ppa.launchpad.net oneiric/main Sources
404 Not Found
Err http://ppa.launchpad.net oneiric/main amd64 Packages
404 Not Found
Ign http://extras.ubuntu.com oneiric/main Translation-en_US
Err http://ppa.launchpad.net oneiric/main i386 Packages
404 Not Found
Ign http://archive.canonical.com maverick/partner Translation-en_US
Ign http://extras.ubuntu.com oneiric/main Translation-en
Ign http://archive.canonical.com maverick/partner Translation-en
Ign http://ppa.launchpad.net oneiric/main Translation-en_US
Ign http://ppa.launchpad.net oneiric/main Translation-en
Ign http://ppa.launchpad.net oneiric/main Translation-en_US
Ign http://ppa.launchpad.net oneiric/main Translation-en
Fetched 72 B in 1s (52 B/s)
W: Failed to fetch http://ppa.launchpad.net/mozillateam/firefox-stable/ubuntu/dists/oneiric/main/source/Sources 404 Not Found

W: Failed to fetch http://ppa.launchpad.net/mozillateam/firefox-stable/ubuntu/dists/oneiric/main/binary-amd64/Packages 404 Not Found

W: Failed to fetch http://ppa.launchpad.net/mozillateam/firefox-stable/ubuntu/dists/oneiric/main/binary-i386/Packages 404 Not Found

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

[2F4U]

The repositories that receive errors are third party repositories, for example

http://ppa.launchpad.net/mozillateam/firefox-stable/ubuntu/dists/oneiric/main/binary-amd64/Packages

and they don't have packages for oneiric (the path simply doesn't exist).