Comment 1 for bug 349781

There is aknown issue with Python in Jaunty and you should update your system immediately. Please see the posting from James Westby below.

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This morning python2.6 version 2.6.1-1ubuntu5 made it in to Jaunty after
being held for a few days for the freeze. Unfortunately this package
contained an ABI break that meant some python extensions no longer
worked, most notably pygtk. In other words if you installed this version
you would see some apps fail to start with a message "undefined symbol:
PyUnicodeUCS4_DecodeUTF8". Most importantly update-manager was affected,
making it harder to upgrade to a fixed version.

  https://bugs.launchpad.net/ubuntu/+source/python2.6/+bug/349467/

Access to the bad packages was blocked, which is why you might have
seen 403 errors if you attempted to upgrade this morning, and fixed
packages have been uploaded as version 2.6.1-1ubuntu5.1.

To find out if you have the bad version of the package installed you
can run

  dpkg -l python2.6 | cat

If the version is not 2.6.1-1ubuntu5 then you are unaffected, you should
just be sure that you don't install that version if it is still
accessible on your mirror.

If you do have the bad version installed then you can upgrade using
apt-get.

  sudo apt-get update
  sudo apt-get upgrade

The fixed packages have only just been made available on the primary
mirror, so you may need to wait a few hours before they can become
available.

Thanks,

James