If ubuntuone fails to start, is probably due to ubuntuone-preferences. If this ran in a console ends up with:
File "/usr/lib/python2.6/ConfigParser.py", line 311, in get raise NoSectionError(section) ConfigParser.NoSectionError: No section: '__main__'
then it's related to this bug.
Binary package hint: xubuntu-default-settings Using Xubuntu 10.04 LTS, using the latest available xubuntu-default-settings (10.04.7). session.sh should not set XDG_CONFIG_DIRS nor XDG_DATA_DIRS. XDG_CONFIG_DIRS is set by /etc/X11/Xsession.d/60xdg_path-on-session and it fails to include /etc/xdg if XDG_CONFIG_DIRS is already set which in turn is doomed to break a lot of applications (ubuntuone-preferences for example). Also, XDG_DATA_DIRS is set by startxfce4 and shouldn't be messed with at this early stage.
FIX: comment the lines regarding XDG in /usr/share/xubuntu/session.sh
#export XDG_CONFIG_DIRS=/etc/xdg/xdg-xubuntu #export XDG_DATA_DIRS=/etc/xdg/xdg-xubuntu exec startxfce4