mcomix crashes while creating a library

When I add comics (in cbt, cbz or cbr) to a library, mcomix crashes with the following error message:

Exception in thread Thread-2:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 808, in __bootstrap_inner
    self.run()
  File "/usr/lib/python2.7/threading.py", line 761, in run
    self.__target(*self.__args, **self.__kwargs)
  File "/usr/lib/python2.7/dist-packages/mcomix/thumbnail_view.py", line 121, in _pixbuf_worker
    pixbuf = self.generate_thumbnail(path, ref.get_model(), ref.get_path())
  File "/usr/lib/python2.7/dist-packages/mcomix/library/book_area.py", line 398, in _get_pixbuf
    pixbuf = self._library.backend.get_book_thumbnail(path) or constants.MISSING_IMAGE_ICON
  File "/usr/lib/python2.7/dist-packages/mcomix/library/backend.py", line 115, in get_book_thumbnail
    thumb = thumbnailer.thumbnail(path)
  File "/usr/lib/python2.7/dist-packages/mcomix/thumbnail_tools.py", line 82, in thumbnail
    pixbuf = image_tools.load_pixbuf(thumbpath)
  File "/usr/lib/python2.7/dist-packages/mcomix/image_tools.py", line 289, in load_pixbuf
    return gtk.gdk.pixbuf_new_from_file(path)
GError: Caricamento dell'immagine «/home/eugene/.local/share/mcomix/library_covers/16261f52cb7ee528ee9ec3b6c0a88c3a.png» non riuscito: Errore critico nel file di immagine PNG: Read Error

09:04:17 WARNING: ! Impossibile prelevare la copertina del libro "/media/Subsistema/eBooks/The Walking Dead/The Walking Dead 103a.cbr"
Exception in thread Thread-5:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 808, in __bootstrap_inner
    self.run()
  File "/usr/lib/python2.7/threading.py", line 761, in run
    self.__target(*self.__args, **self.__kwargs)
  File "/usr/lib/python2.7/dist-packages/mcomix/thumbnail_view.py", line 121, in _pixbuf_worker
    pixbuf = self.generate_thumbnail(path, ref.get_model(), ref.get_path())
  File "/usr/lib/python2.7/dist-packages/mcomix/library/book_area.py", line 398, in _get_pixbuf
    pixbuf = self._library.backend.get_book_thumbnail(path) or constants.MISSING_IMAGE_ICON
  File "/usr/lib/python2.7/dist-packages/mcomix/library/backend.py", line 115, in get_book_thumbnail
    thumb = thumbnailer.thumbnail(path)
  File "/usr/lib/python2.7/dist-packages/mcomix/thumbnail_tools.py", line 82, in thumbnail
    pixbuf = image_tools.load_pixbuf(thumbpath)
  File "/usr/lib/python2.7/dist-packages/mcomix/image_tools.py", line 289, in load_pixbuf
    return gtk.gdk.pixbuf_new_from_file(path)
GError: Caricamento dell'immagine «/home/eugene/.local/share/mcomix/library_covers/16261f52cb7ee528ee9ec3b6c0a88c3a.png» non riuscito: Errore critico nel file di immagine PNG: Read Error

Exception in thread Thread-9:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 808, in __bootstrap_inner
    self.run()
  File "/usr/lib/python2.7/threading.py", line 761, in run
    self.__target(*self.__args, **self.__kwargs)
  File "/usr/lib/python2.7/dist-packages/mcomix/thumbnail_view.py", line 121, in _pixbuf_worker
    pixbuf = self.generate_thumbnail(path, ref.get_model(), ref.get_path())
  File "/usr/lib/python2.7/dist-packages/mcomix/library/book_area.py", line 398, in _get_pixbuf
    pixbuf = self._library.backend.get_book_thumbnail(path) or constants.MISSING_IMAGE_ICON
  File "/usr/lib/python2.7/dist-packages/mcomix/library/backend.py", line 115, in get_book_thumbnail
    thumb = thumbnailer.thumbnail(path)
  File "/usr/lib/python2.7/dist-packages/mcomix/thumbnail_tools.py", line 82, in thumbnail
    pixbuf = image_tools.load_pixbuf(thumbpath)
  File "/usr/lib/python2.7/dist-packages/mcomix/image_tools.py", line 289, in load_pixbuf
    return gtk.gdk.pixbuf_new_from_file(path)
GError: Caricamento dell'immagine «/home/eugene/.local/share/mcomix/library_covers/16261f52cb7ee528ee9ec3b6c0a88c3a.png» non riuscito: Errore critico nel file di immagine PNG: Read Error

Errore di bus (core dump creato)

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: mcomix 0.99-1
ProcVersionSignature: Ubuntu 3.11.0-2.5-generic 3.11.0-rc5
Uname: Linux 3.11.0-2-generic x86_64
ApportVersion: 2.12.1-0ubuntu2
Architecture: amd64
Date: Tue Aug 20 09:05:38 2013
InstallationDate: Installed on 2013-01-06 (225 days ago)
InstallationMedia: Ubuntu 12.04.1 LTS "Precise Pangolin" - Release amd64 (20120823.1)
MarkForUpload: True
PackageArchitecture: all
SourcePackage: mcomix
UpgradeStatus: Upgraded to saucy on 2013-07-01 (49 days ago)