frequent system internal error

[Paola Salviato]

Hello there,

I keep getting this error, very frequently:

Error Type: <type 'exceptions.TypeError'>
Error Value: 'NoneType' object is unsubscriptable
  File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 2316, in 
<module>
    main()
  File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 2313, in main
    backend.dispatcher(sys.argv[1:])
  File : /usr/lib/python2.5/site-packages/packagekit/backend.py, line 
600, in dispatcher
    self.dispatch_command(args[0], args[1:])
  File : /usr/lib/python2.5/site-packages/packagekit/backend.py, line 
508, in dispatch_command
    self.get_updates(filters)
  File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 1769, in 
get_updates
    self._check_init()
  File : /usr/share/PackageKit/helpers/yum/yumBackend.py, line 1996, in 
_check_init
    self.yumbase.repos.doSetup()
  File : /usr/lib/python2.5/site-packages/yum/repos.py, line 71, in doSetup
    self.ayum.plugins.run('postreposetup')
  File : /usr/lib/python2.5/site-packages/yum/plugins.py, line 178, in run
    func(conduitcls(self, self.base, conf, **kwargs))
  File : /usr/lib/yum-plugins/rpm-warm-cache.py, line 32, in 
postreposetup_hook
    cmd = commands[0]
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Is there anybody who could help me fixing it?

Cheers,

Paola