Description of problem: From out of the blue (not in response to any known user command) a dialog box appears on the desktop "An internal system error has occurred.  A problem that we were not expecting has occurred.  Please report htis bug in your distribution bugtracker with the error description."  There is no readily-identifiable process associated with the dialog.  There is a scroll box "More details" whose contents I will copy+paste below.


Version-Release number of selected component (if applicable):
PackageKit-0.5.1-1.fc12.i686
yum-3.2.23-13.fc12.noarch


How reproducible: unknown; happened twice in same session, a few minutes apart.


Steps to Reproduce:
1. login, run "yum update" (updates anaconda and pungi) and finish yum, wait a couple minutes
2.
3.
  
Actual results:  Dialog box as in Description, with "More details":
-----
  File "/usr/lib/python2.6/site-packages/yum/yumRepo.py", line 1195, in _commonLoadRepoXML
    result = self._getFileRepoXML(local, text)
  File "/usr/lib/python2.6/site-packages/yum/yumRepo.py", line 976, in _getFileRepoXML
    cache=self.http_caching == 'all')
  File "/usr/lib/python2.6/site-packages/yum/yumRepo.py", line 754, in _getFile
    result = self.mediafunc(local = local, checkfunc = checkfunc, relative = relative, text = text, copy_local = copy_local, url = url, mediaid = self.mediaid, name = self.name, discnum = discnum, range = (start, end))
  File "/usr/share/PackageKit/helpers/yum/yumBackend.py", line 2863, in MediaGrabber
    manager = MediaManager()
  File "/usr/share/PackageKit/helpers/yum/yumMediaManager.py", line 101, in __init__
    raise NotImplemented
TypeError: exceptions must be classes or instances, not NotImplementedType
-----

Expected results: no dialog box complaining of mysterious error


Additional info: