I update my system and all is fine but then after some time a sign appears at the top panel and tells me something is wrong with the some repositories and tells me to do a check for update, when I do I get this error
W:GPG error: http://us.archive.ubuntu.com precise Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <email@example.com> W:Failed to fetch http://archive.canonical.com/ubuntu/dists/precise/partner/i18n/Index No Hash entry in Release file /var/lib/apt/lists/partial/archive.canonical.com_ubuntu_dists_precise_partner_i18n_Index W:Failed to fetch http://ppa.launchpad.net/clipgrab-team/ppa/ubuntu/dists/precise/main/i18n/Index No Hash entry in Release file /var/lib/apt/lists/partial/ppa.launchpad.net_clipgrab-team_ppa_ubuntu_dists_precise_main_i18n_Index W:Failed to fetch http://ppa.launchpad.net/otto-kesselgulasch/gimp/ubuntu/dists/precise/main/i18n/Index No Hash entry in Release file /var/lib/apt/lists/partial/ppa.launchpad.net_otto-kesselgulasch_gimp_ubuntu_dists_precise_main_i18n_Index E:Some index files failed to download. They have been ignored, or old ones used instead.
any help please???