Cannot update system or install packages.

[gszx1337]

I just switched over from Ubuntu to Fedora 12 (KDE) and am having a problem with installing packages and updating my system.

When I use KPackageKit to update my system, I get this error:

Error Type: 
Error Value: Error getting repository data for installed, repository not found
File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 3125, in 
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)

Whenever I try to install Google Chrome, I get this error:

An unknown error happened

If anyone can help, I'd greatly appreciate it,
~GSZX1337

[glennzo]

Open a terminal and type

su -c 'yum clean all'
yum check-update
su -c 'yum update'

[gszx1337]

Thanks glennzo, worked like a charm.