[ubuntu] Update problem

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http://ubuntuforums.org – Hi Ubuntu User I am a new ubuntu user. When i first install ubuntu it seems good to work. But recently when i run the command to the terminal sudo apt-get update it shows some error which is Err http://ppa.launchpad.net precise/main Sources 404 Not Found Err http://ppa.launchpad.net precise/main i386 Packages 404 Not Found W: Failed to fetch http://ppa.launchpad.net/cheleb/blen...source/Sources 404 Not Found W: Failed to fetch http://ppa.launchpad.net/cheleb/blen...-i386/Packages 404 Not Found E: Some index f (Hardware)