Ubuntu Software Center падает при запуске

Когда я пытаюсь открыть центр программного обеспечения, он открывается, но в окне ничего не появляется и закрывается через 5 секунд. он работал раньше, а затем я сделал чистку PPA, а затем он не открывается. ppa, который я пытался удалить, был ppa: sunab / kdenlive-release после того, как я очистил этот ppa, терминал сказал, что возник конфликт. он предложил мне решение (которое я не читал), и я принял его. после того, как это будет сделано, центр программного обеспечения не откроет центр программного обеспечения

. Здесь вывод от терминала

2013-04-18 11:56:47,034 - softwarecenter.ui.gtk3.app - INFO - setting up proxy 'None'
2013-04-18 11:56:47,050 - softwarecenter.db.database - INFO - open() database: path=None use_axi=True use_agent=True
2013-04-18 11:56:48,620 - softwarecenter.backend.reviews - WARNING - Could not get usefulness from server, no username in config file
2013-04-18 11:56:49,354 - softwarecenter.ui.gtk3.app - INFO - show_available_packages: search_text is '', app is None.
2013-04-18 11:56:50,782 - softwarecenter.db.pkginfo_impl.aptcache - INFO - aptcache.open()
Traceback (most recent call last):
  File "/usr/share/software-center/softwarecenter/db/pkginfo_impl/aptcache.py", line 243, in open
    self._cache = apt.Cache(GtkMainIterationProgress())
  File "/usr/lib/python2.7/dist-packages/apt/cache.py", line 102, in __init__
    self.open(progress)
  File "/usr/lib/python2.7/dist-packages/apt/cache.py", line 145, in open
    self._cache = apt_pkg.Cache(progress)
SystemError: E:Type 'ain' is not known on line 3 in source list /etc/apt/sources.list.d/sunab-kdenlive-release-precise.list, E:The list of sources could not be read., E:The package lists or status file could not be parsed or opened.
2013-04-18 11:56:54,320 - softwarecenter.db.enquire - ERROR - _get_estimate_nr_apps_and_nr_pkgs failed
Traceback (most recent call last):
  File "/usr/share/software-center/softwarecenter/db/enquire.py", line 115, in _get_estimate_nr_apps_and_nr_pkgs
    tmp_matches = enquire.get_mset(0, len(self.db), None, xfilter)
  File "/usr/share/software-center/softwarecenter/db/appfilter.py", line 89, in __call__
    if (not pkgname in self.cache and
  File "/usr/share/software-center/softwarecenter/db/pkginfo_impl/aptcache.py", line 263, in __contains__
    return self._cache.__contains__(k)
AttributeError: 'NoneType' object has no attribute '__contains__'
Traceback (most recent call last):
  File "/usr/bin/software-center", line 176, in 
    app.run(args)
  File "/usr/share/software-center/softwarecenter/ui/gtk3/app.py", line 1422, in run
    self.show_available_packages(args)
  File "/usr/share/software-center/softwarecenter/ui/gtk3/app.py", line 1352, in show_available_packages
    self.view_manager.set_active_view(ViewPages.AVAILABLE)
  File "/usr/share/software-center/softwarecenter/ui/gtk3/session/viewmanager.py", line 154, in set_active_view
    view_widget.init_view()
  File "/usr/share/software-center/softwarecenter/ui/gtk3/panes/availablepane.py", line 171, in init_view
    self.apps_filter)
  File "/usr/share/software-center/softwarecenter/ui/gtk3/views/catview_gtk.py", line 238, in __init__
    self.build(desktopdir)
  File "/usr/share/software-center/softwarecenter/ui/gtk3/views/catview_gtk.py", line 511, in build
    self._build_homepage_view()
  File "/usr/share/software-center/softwarecenter/ui/gtk3/views/catview_gtk.py", line 271, in _build_homepage_view
    self._append_whats_new()
  File "/usr/share/software-center/softwarecenter/ui/gtk3/views/catview_gtk.py", line 450, in _append_whats_new
    whats_new_cat = self._update_whats_new_content()
  File "/usr/share/software-center/softwarecenter/ui/gtk3/views/catview_gtk.py", line 439, in _update_whats_new_content
    docs = whats_new_cat.get_documents(self.db)
  File "/usr/share/software-center/softwarecenter/db/categories.py", line 124, in get_documents
    nonblocking_load=False)
  File "/usr/share/software-center/softwarecenter/db/enquire.py", line 317, in set_query
    self._blocking_perform_search()
  File "/usr/share/software-center/softwarecenter/db/enquire.py", line 212, in _blocking_perform_search
    matches = enquire.get_mset(0, self.limit, None, xfilter)
  File "/usr/share/software-center/softwarecenter/db/appfilter.py", line 89, in __call__
    if (not pkgname in self.cache and
  File "/usr/share/software-center/softwarecenter/db/pkginfo_impl/aptcache.py", line 263, in __contains__
    return self._cache.__contains__(k)
AttributeError: 'NoneType' object has no attribute '__contains__'

. Я использую 12.04 64 бит