各位大侠，我的红旗桌面6.0SP3系统经常自动提示：系统有一个错误，错误详情（软件包管理器错误详细信息）如下：
Error Type: yum.Errors.RepoError
Error Value: Cannot retrieve repository metadata (repomd.xml) for repository: extras. Please verify its path and try again
File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 2289, in ?
main()
File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 2286, in main
backend.dispatcher(sys.argv[1:])
File : /usr/lib/python2.4/site-packages/packagekit/backend.py, line 600, in dispatcher
self.dispatch_command(args[0], args[1:])
File : /usr/lib/python2.4/site-packages/packagekit/backend.py, line 504, in dispatch_command
self.get_distro_upgrades()
File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 1684, in get_distro_upgrades
pkgs = self.yumbase.pkgSack.returnNewestByName(name='preupgrade')
File : /usr/lib/python2.4/site-packages/yum/__init__.py, line 598, in
pkgSack = property(fget=lambda self: self._getSacks(),
File : /usr/lib/python2.4/site-packages/yum/__init__.py, line 434, in _getSacks
self.repos.populateSack(which=repos)
File : /usr/lib/python2.4/site-packages/yum/repos.py, line 251, in populateSack
sack.populate(repo, mdtype, callback, cacheonly)
File : /usr/lib/python2.4/site-packages/yum/yumRepo.py, line 160, in populate
if self._check_db_version(repo, mydbtype):
File : /usr/lib/python2.4/site-packages/yum/yumRepo.py, line 217, in _check_db_version
return repo._check_db_version(mdtype)
File : /usr/lib/python2.4/site-packages/yum/yumRepo.py, line 1111, in _check_db_version
repoXML = self.repoXML
File : /usr/lib/python2.4/site-packages/yum/yumRepo.py, line 1270, in
repoXML = property(fget=lambda self: self._getRepoXML(),
File : /usr/lib/python2.4/site-packages/yum/yumRepo.py, line 1266, in _getRepoXML
raise Errors.RepoError, msg
各位，请抽空帮帮忙吧！