[ubuntu] Bumblebee is not working

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http://ubuntuforums.org – Hello all, I am using Dell Xps 15 . I have installed bumblebee for my Nvidia graphic card. Before it was working as the fan is been shut down of graphic card but somehow it's not working and battery is getting consumed alot. I am getting this error.. W: Failed to fetch http://ppa.launchpad.net/mj-casalogi...source/Sources 404 Not Found W: Failed to fetch http://ppa.launchpad.net/mj-casalogi...amd64/Packages 404 Not Found W: Failed to fetch http://ppa.launchpad.net/mj-casalogi...-i386/Packages 404 Not Found E: Some index files failed to download. They have been ignore (Hardware)