When i open download manager and i try to check for updates, it fail and says me: downloading repository failed and to check my internet connection. I'm sure i am connected (tested too) and that's what it appear behind:
"W:GPG error: http://dl.dropbox.com stable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY BACCFCFB98DB2EDC, W:Failed to fetch http://ppa.launchpad.net/iaz/battery...source/Sources 404 Not Found
, W:Failed to fetch http://ppa.launchpad.net/iaz/battery...-i386/Packages 404 Not Found
, E:Some index files failed to download. They have been ignored, or old ones used instead."