Você precisa remover todos esses pacotes:
sudo apt-get remover abiword abiword-comum abiword-plugin-gramática abiword-plugin-mathview ás-de-pinguins audacioso-plugins audiômetro navegador-cromo navegador-cromo-l10n codificadores-crom-ffmpeg-elementar-icon-theme esound -common galografia gdebi gdebi-core giblib1 gnome-icon-tema-completo gnome-mplayer gnome-system-tools gnome-time-admin gnumeric gnumeric-common gnumeric-doc gipview gtk2-motores-pixbuf guvcview hardinfo indicador-status-provedor-pidgin leafpad libabiword-3,0-libaiksaurus 1.2-0c2a libaiksaurus-1,2-dados libaiksaurusgtk-1.2-0c2a libaudclient2 libaudcore1 libaudiofile1 libavcodec53 libavformat53 libavutil51 libbinio1ldbl libcddb2 libcompfaceg1 libcue1 libdca0 libdirectfb-1,2-9 libdiscid0 libdvdnav4 libdvdread4 libenca0 libencode-localidade-perl libept1.4.12 libesd0 libexo- 1-0 libexo-common libfaad2 libfm-gtk3 libfm-libl libfm-gtk libfm-perl-perl libgdome2-libgdome2-cpp-smart0c2a libglade2-0 libgoffice-0.8-8 libgoffice-0.8- 8-comum libgringotts2 libgsf-1-114 libgsf-1-comum libgsm1 libgtkmathview0c2a libhtml-forma-perl libhtml-formato-perl libhtml-parser-perl libhtml-tagset-perl libhtml-tree-perl libhttp-cookies-perl libhttp-daemon- perl libhttp-data-perl libhttp-mensagem-perl libhttp-negociar-perl libid3tag0 libimlib2 libio-socket-ssl-perl libjpeg-prog liblink-grammar4 libloudmouth1-0 liblwp-mediatypes-perl liblwp-protocolo-https-perl libmailtools-perl libmcrypt4 libmcs1 libmenu-cache3 libmms0 libmowgli2 libmusicbrainz3-6 libnet-dbus-perl libnet-http-perl libnet-ssleay-perl lib libro29 libobt2 libonib2 liboobs-1-5 libopenal1 libopts25 libots0 libpisock9 libpolkit-gtk-1-0 libpostproc52 libresid-builder0c2a libschroedinger-1.0 -0 libsidplay2 libsvga1 libswscale2 libtar0 libtie-ixhash-perl libtimedate-perl libts-0.0-0 libnibonf4.6 liburi-perl lib libra1 libvd libu lib1 libweb lib0v-1.2-4 libwvstreams4.6 base libwvstreams4.6-extras libwww-perl libwww-robotrules -perl libxfce4ui-1-0 libxfce4util-bin libxfce4 util-common libxfce4util4 libxfcegui4-4 libxfconf-0-2 libxml-parser-perl libxml-twig-perl libxml-xpath-perl libxss1 libxvidcore4 link-gramática-dicionários-en lm-sensores lubuntu-obra lubuntu-core lubuntu-default-settings lubuntu-desktop lubuntu-ícone-tema lxappearance lxappearance-obconf lxde-comum lxde-core lxdm lxinput lxkeymap lxlauncher lxmenu-dados lxpanel lxpanel-indicador-applet-plugin lxrandr lxsession lxsession-edição lxshortcut lxtask lxterminal mplayer ntp mtpaint obconf openbox openbox-temas osmo pcmanfm pidgin pidgin-dados pidgin-libnotify pidgin-microblog plymouth-tema-lubuntu-logo plymouth-tema-lubuntu-texto scrot sylpheed sylpheed-doc sylpheed-i18n sylpheed-plugins synaptic sistema-ferramentas-backends transmissão tsconf ttf-lyx uvcdynctrl uvcdynctrl- dados wvdial xfburn xfce-keyboard-atalhos xfce4-power-manager xfce4-power-gerenciador de dados xfconf xfonts-100dpi xpad xcreensaver xscreensaver-data
depois reinstale o ubuntu-desktop
por
sudo apt-get install --reinstalar o ubuntu-desktop