Comment 7 for bug 361180

Hi.

I had the same problem after upgrading from Intrepid to Jaunty. Tried running pycentral as sugested by Michael:
$ sudo pycentral -v pkginstall software-properties-gtk
pycentral: pycentral -v pkginstall software-properties-gtk
pycentral: reading /usr/share/pyshared-data/software-properties-gtk
pycentral: dpkg-query -s software-properties-gtk
pycentral: avail=['2.5', '2.6'], pkg=>= 2.4, install=['2.5', '2.6']
pycentral: install package software-properties-gtk
pycentral: link shared files python2.5/software-properties-gtk
pycentral: byte-compile files (11/11) python2.5
pycentral: ['/usr/lib/python2.5/site-packages/softwareproperties/gtk/CdromProgress.py', '/usr/lib/python2.5/site-packages/softwareproperties/gtk/DialogAdd.py', '...']
pycentral: link shared files python2.6/software-properties-gtk
pycentral: byte-compile files (11/11) python2.6
pycentral: ['/usr/lib/python2.6/dist-packages/softwareproperties/gtk/CdromProgress.py', '/usr/lib/python2.6/dist-packages/softwareproperties/gtk/DialogAdd.py', '...']

Still get the same error when trying to run gksu. Then I came over another bug that gave me a solution:
$ sudo apt-get install --reinstall python-apt update-manager-core update-manager python python-central synaptic gksu python-software-properties python-glade2 python-gtk2 software-properties-gtk
$ sudo apt-get update && sudo apt-get upgrade
$ sudo dpkg-reconfigure python-software-properties
ref: https://bugs.launchpad.net/ubuntu/+source/python-apt/+bug/319714