Fedora 12 update problem

I just installed fedora 12 as an update of a fedore 11 system. This morning I saw 683 updates proposed for my system. I clicked on "Install Updates" button and had, some seconds after this message: ______________________________________ Error Type: <class 'yum.Errors.RepoError'> Error Value: Error getting repository data for installed, repository not found File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 3125, in <module> main() File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 3122, in main backend.dispatcher(sys.argv[1:]) File : /usr/lib/python2.6/site-packages/packagekit/backend.py, line 710, in dispatcher self.dispatch_command(args[0], args[1:]) File : /usr/lib/python2.6/site-packages/packagekit/backend.py, line 657, in dispatch_command self.update_packages(only_trusted, package_ids) File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 1948, in update_packages signed = self._is_package_repo_signed(pkg) File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 1437, in _is_package_repo_signed repo = self.yumbase.repos.getRepo(pkg.repoid) File : /usr/lib/python2.6/site-packages/yum/repos.py, line 121, in getRepo 'Error getting repository data for $s, repository not found' $ (repoid) ________________________________________ Any help? ___________________________________________ Cordialement / Best Regards Taoufik GABSI Géophysique Spatiale et Planétaire Institut de Physique du Globe de Paris 4, avenue de Neptune - 94107 SAINT MAUR cedex - FRANCE gabsi(a)ipgp.fr Tel +33 (0)1 45 11 41 49 Fax +33 (0)1 45 11 41 10