I've reinstalled Ubuntu again! The following is from a fresh reboot: 1.- 'sudo which perl' output: ----------------------------------------------------------------------------------------------------- /usr/bin/perl ----------------------------------------------------------------------------------------------------- 2.- users-admin started. 3.- 'ps ax | grep perl' output: ----------------------------------------------------------------------------------------------------- 1847 ? S 0:00 /usr/bin/perl /usr/share/system-tools-backends-2.0/scripts/SystemToolsBackends.pl -m Platform 1853 ? S 0:00 /usr/bin/perl /usr/share/system-tools-backends-2.0/scripts/SystemToolsBackends.pl -m UsersConfig 1855 ? S 0:00 /usr/bin/perl /usr/share/system-tools-backends-2.0/scripts/SystemToolsBackends.pl -m GroupsConfig 1857 ? S 0:00 /usr/bin/perl /usr/share/system-tools-backends-2.0/scripts/SystemToolsBackends.pl -m UserConfig 1865 pts/0 R+ 0:00 grep --color=auto perl ----------------------------------------------------------------------------------------------------- 4.- 'ps ax | grep .p' output : ----------------------------------------------------------------------------------------------------- 7 ? S< 0:00 [cpuset] 8 ? S< 0:00 [khelper] 13 ? S< 0:00 [kacpid] 14 ? S< 0:00 [kacpi_notify] 15 ? S< 0:00 [kacpi_hotplug] 18 ? S< 0:00 [ksuspend_usbd] 24 ? S 0:00 [pdflush] 25 ? S 0:00 [pdflush] 26 ? S< 0:00 [kswapd0] 28 ? S< 0:00 [ecryptfs-kthrea] 29 ? S< 0:00 [crypto/0] 36 ? S< 0:00 [kstriped] 37 ? S< 0:00 [kmpathd/0] 38 ? S< 0:00 [kmpath_handlerd] 39 ? S< 0:00 [ksnapd] 282 ? S< 0:00 [khpsbpkt] 425 ? S 0:00 upstart-udev-bridge --daemon 656 ? S< 0:00 [kpsmoused] 709 ? Ss 0:00 dd bs=1 if=/proc/kmsg of=/var/run/rsyslog/kmsg 728 ? S< 0:00 [pccardd] 805 ? S< 0:00 [ipw2200/0] 869 ? Ss 0:00 avahi-daemon: chroot helper 890 ? Ss 0:00 acpid -c /etc/acpi/events -s /var/run/acpid.socket 915 ? Ss 0:00 /usr/sbin/kerneloops 981 ? S 0:00 /sbin/wpa_supplicant -u -s 1049 ? S 0:00 /usr/lib/gdm/gdm-simple-slave --display-id /org/gnome/DisplayManager/Display1 1050 ? Ss 0:00 /usr/sbin/cupsd -C /etc/cups/cupsd.conf 1051 tty7 Ss+ 0:08 /usr/bin/X :0 -br -verbose -auth /var/run/gdm/auth-for-gdm-9I5Vxt/database -nolisten tcp vt7 1147 ? S 0:00 /usr/lib/hal/hald-addon-ipw-killswitch 1217 ? S 0:00 hald-addon-input: Listening on /dev/input/event1 /dev/input/event0 /dev/input/event2 /dev/input/event5 /dev/input/event4 1225 ? S 0:00 hald-addon-storage: polling /dev/sr0 (every 2 sec) 1231 ? S 0:00 /usr/lib/hal/hald-addon-cpufreq 1232 ? S 0:00 hald-addon-acpi: listening on acpid socket /var/run/acpid.socket 1338 ? S 0:00 /usr/lib/devicekit-power/devkit-power-daemon 1473 ? Ss 0:00 /usr/bin/ssh-agent /usr/bin/dbus-launch --exit-with-session /usr/bin/pulse-session gnome-session 1476 ? S 0:00 /usr/bin/dbus-launch --exit-with-session /usr/bin/pulse-session gnome-session 1477 ? Ss 0:00 /bin/dbus-daemon --fork --print-pid 7 --print-address 9 --session 1481 ? Ssl 0:00 /usr/bin/pulseaudio --start 1484 ? S 0:00 /usr/lib/pulseaudio/pulse/gconf-helper 1551 ? S 0:00 /bin/sh /usr/bin/compiz 1635 ? S 0:01 /usr/bin/compiz.real --ignore-desktop-hints --replace --sm-client-id 10cd12868114f4a26e125709716333260900000014340022 move resize place decoration animation ccp 1636 ? S 0:03 gnome-panel 1639 ? Ssl 0:00 /usr/lib/bonobo-activation/bonobo-activation-server --ac-activate --ior-output-fd=20 1641 ? Ss 0:00 /bin/sh -c /usr/bin/compiz-decorator 1647 ? S 0:00 gnome-power-manager 1648 ? S 0:00 nm-applet --sm-disable 1649 ? S 0:00 python /usr/share/system-config-printer/applet.py 1651 ? S 0:00 bluetooth-applet 1652 ? S 0:00 /usr/lib/policykit-1-gnome/polkit-gnome-authentication-agent-1 1654 ? S 0:00 update-notifier --startup-delay=60 1663 ? S 0:00 gnome-volume-control-applet 1671 ? S 0:00 /usr/lib/gnome-applets/trashapplet --oaf-activate-iid=OAFIID:GNOME_Panel_TrashApplet_Factory --oaf-ior-fd=18 1676 ? S 0:00 /usr/lib/policykit-1/polkitd 1679 ? S 0:00 devkit-disks-daemon: polling /dev/sr0 1682 ? S 0:00 /usr/lib/gvfs/gvfs-gphoto2-volume-monitor 1688 ? S 0:00 /usr/lib/gvfs/gvfsd-trash --spawner :1.8 /org/gtk/gvfs/exec_spaw/0 1711 ? S 0:00 /sbin/dhclient -d -sf /usr/lib/NetworkManager/nm-dhcp-client.action -pf /var/run/dhclient-eth0.pid -lf /var/lib/dhcp3/dhclient-341228ed-4c2d-4d84-ae0f-07f65a19288a-eth0.lease -cf /var/run/nm-dhclient-eth0.conf eth0 1719 ? S 0:00 /usr/lib/indicator-applet/indicator-applet-session --oaf-activate-iid=OAFIID:GNOME_FastUserSwitchApplet_Factory --oaf-ior-fd=19 1721 ? S 0:00 /usr/lib/indicator-applet/indicator-applet --oaf-activate-iid=OAFIID:GNOME_IndicatorApplet_Factory --oaf-ior-fd=26 1791 ? S 0:00 /usr/lib/gvfs/gvfsd-burn --spawner :1.8 /org/gtk/gvfs/exec_spaw/2 1808 ? S 0:00 gnome-pty-helper 1809 pts/0 Ss 0:00 bash 1835 ? S 0:00 /usr/bin/python /usr/sbin/aptd 1847 ? S 0:00 /usr/bin/perl /usr/share/system-tools-backends-2.0/scripts/SystemToolsBackends.pl -m Platform 1853 ? S 0:00 /usr/bin/perl /usr/share/system-tools-backends-2.0/scripts/SystemToolsBackends.pl -m UsersConfig 1855 ? S 0:00 /usr/bin/perl /usr/share/system-tools-backends-2.0/scripts/SystemToolsBackends.pl -m GroupsConfig 1857 ? S 0:00 /usr/bin/perl /usr/share/system-tools-backends-2.0/scripts/SystemToolsBackends.pl -m UserConfig 1866 pts/0 R+ 0:00 ps ax 1867 pts/0 R+ 0:00 grep --color=auto .p ----------------------------------------------------------------------------------------------------- 5.- 'ps ax | grep system-tools' output: ----------------------------------------------------------------------------------------------------- 1845 ? S 0:00 /usr/sbin/system-tools-backends 1847 ? S 0:00 /usr/bin/perl /usr/share/system-tools-backends-2.0/scripts/SystemToolsBackends.pl -m Platform 1853 ? S 0:00 /usr/bin/perl /usr/share/system-tools-backends-2.0/scripts/SystemToolsBackends.pl -m UsersConfig 1855 ? S 0:00 /usr/bin/perl /usr/share/system-tools-backends-2.0/scripts/SystemToolsBackends.pl -m GroupsConfig 1857 ? S 0:00 /usr/bin/perl /usr/share/system-tools-backends-2.0/scripts/SystemToolsBackends.pl -m UserConfig 1869 pts/0 R+ 0:00 grep --color=auto system-tools ----------------------------------------------------------------------------------------------------- 6.- I deleted the user using users-admin. 7.- 'sudo which system-tools-backends' output: ----------------------------------------------------------------------------------------------------- /usr/sbin/system-tools-backends ----------------------------------------------------------------------------------------------------- 8.- 'sudo system-tools-backends' output: ----------------------------------------------------------------------------------------------------- ** (system-tools-backends:1890): CRITICAL **: Could not get a valid destination, original one was: / ----------------------------------------------------------------------------------------------------- 9.- I closed users-admin and restarted my computer. 10.- 'sudo which system-tools-backends' output: nothing 11.- 'sudo system-tools-backends' output: ----------------------------------------------------------------------------------------------------- ** (system-tools-backends:1827): CRITICAL **: Could not get a valid destination, original one was: / -----------------------------------------------------------------------------------------------------