Comment 6 for bug 1100219

Just installed Kubuntu 12.10 AMD64 desktop

get same problem trying to run bleacbit as root
gksudo -k bleachbit did not work - did get error message:
Error copying '/tmp/kde-jay/xauth-1000-_0' to '/tmp/libgksu-db2kSu': No such file or directory

but, in /tmp is:
drwx------ 2 jay jay 4096 Mar 12 18:45 libgksu-db2kSu
in there is
-rw------- 1 jay jay 0 Mar 12 18:45 .Xauthority

note: zero-length.
and /tmp/kde-jay is empty.

nothing interestin in /var/log/Xorg.0.log
no errors in /var/log/auth.log

weird message in syslog
Mar 12 18:53:45 pc-14-large dbus[780]: [system] Activating service name='org.kde.powerdevil.backlighthelper' (using servicehelper)
Mar 12 18:53:45 pc-14-large org.kde.powerdevil.backlighthelper: QDBusConnection: system D-Bus connection created before QCoreApplication. Application may misbehave.
Mar 12 18:53:45 pc-14-large dbus[780]: [system] Successfully activated service 'org.kde.powerdevil.backlighthelper'
Mar 12 18:55:00 pc-14-large dbus[780]: [system] Activating service name='org.kde.powerdevil.backlighthelper' (using servicehelper)
Mar 12 18:55:00 pc-14-large org.kde.powerdevil.backlighthelper: QDBusConnection: system D-Bus connection created before QCoreApplication. Application may misbehave.
Mar 12 18:55:00 pc-14-large dbus[780]: [system] Successfully activated service 'org.kde.powerdevil.backlighthelper'

hope this helps.
Jay