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http://askubuntu.com – When i clicked check this error message came up. But it does not come up when update manager strarts automatically. When you open update manager this error comes up. Any ideas on how to fix it? Details: *W:GPG error: (http://ppa.launchpad.net precise Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY FC8CA6FE7B1FEC7C, W:Failed to fetch (http://ppa.launchpad.net/jonabeck/ppa/ubuntu/dists/precise/main/binary-a... 404 Not Found , W:Failed to fetch (http://ppa.launchpad.net/jonabeck/ppa/ubuntu/dists/precise/main/binary-i... (HowTos)