Se você obtiver, ao chamar um programa no terminal, os erros abaixo:

/usr/lib/python2.5/site-packages/apt/__init__.py:18: FutureWarning: apt API not stable yet
  warnings.warn("apt API not stable yet", FutureWarning)
Traceback (most recent call last):
  File "./ubuntu-tweak.py", line 68, in <module>
    launcher = TweakLauncher()
  File "./ubuntu-tweak.py", line 38, in __init__
    from MainWindow import MainWindow
  File "/usr/share/ubuntu-tweak/MainWindow.py", line 82, in <module>
    from AutoStart import AutoStart
  File "/usr/share/ubuntu-tweak/AutoStart.py", line 26, in <module>
    from xdg.DesktopEntry import DesktopEntry
ImportError: No module named xdg.DesktopEntry

Basta apenas instalar o programa "python-xdg" que tudo vai se resolver...

Nos Linux Debian based:

sudo apt-get install python-xdg

Até a próxima dica!!!!!
;-)