Here's what happened, in case it helps anyone. From my "/var/log/apt/term.log" ("(Reading database ... " lines removed for your convenience.)
Log started: 2011-09-12 18:26:54 (Reading database ... 406284 files and directories currently installed.) Removing ubuntu-desktop ... Removing unity ... Removing compiz ... Removing compiz-gnome ... Removing compiz-plugins-main ... Removing compiz-plugins-main-default ... Removing compizconfig-backend-gconf ... Removing compizconfig-settings-manager ... Removing python-compizconfig ... Removing libcompizconfig0 ... Processing triggers for gnome-menus ... Processing triggers for desktop-file-utils ... Processing triggers for bamfdaemon ... Rebuilding /usr/share/applications/bamf.index... Processing triggers for man-db ... Processing triggers for gconf2 ... Processing triggers for hicolor-icon-theme ... Processing triggers for libc-bin ... ldconfig deferred processing now taking place (Reading database ... 405828 files and directories currently installed.) Preparing to replace compiz-plugins 1:0.9.5.92+bzr2791-0ubuntu2 (using .../compiz-plugins_1%3a0.9.5.94+bzr2803-0ubuntu1_amd64.deb) ... Unpacking replacement compiz-plugins ... Preparing to replace compiz-plugins-default 1:0.9.5.92+bzr2791-0ubuntu2 (using .../compiz-plugins-default_1%3a0.9.5.94+bzr2803-0ubuntu1_amd64.deb) ... Unpacking replacement compiz-plugins-default ... Preparing to replace libdecoration0 1:0.9.5.92+bzr2791-0ubuntu2 (using .../libdecoration0_1%3a0.9.5.94+bzr2803-0ubuntu1_amd64.deb) ... Unpacking replacement libdecoration0 ... Preparing to replace compiz-core 1:0.9.5.92+bzr2791-0ubuntu2 (using .../compiz-core_1%3a0.9.5.94+bzr2803-0ubuntu1_amd64.deb) ... Unpacking replacement compiz-core ... Preparing to replace python-pyatspi2 2.1.90-0ubuntu1 (using .../python-pyatspi2_2.1.91-0ubuntu1_all.deb) ... Unpacking replacement python-pyatspi2 ... Preparing to replace simple-scan 3.1.5-0ubuntu1 (using .../simple-scan_3.1.91-0ubuntu1_amd64.deb) ... Unpacking replacement simple-scan ... Processing triggers for gnome-menus ... Processing triggers for desktop-file-utils ... Processing triggers for bamfdaemon ... Rebuilding /usr/share/applications/bamf.index... Processing triggers for man-db ... Processing triggers for libglib2.0-0:i386 ... Processing triggers for libglib2.0-0 ... Setting up compiz-core (1:0.9.5.94+bzr2803-0ubuntu1) ... Setting up libdecoration0 (1:0.9.5.94+bzr2803-0ubuntu1) ... Setting up compiz-plugins-default (1:0.9.5.94+bzr2803-0ubuntu1) ... Setting up compiz-plugins (1:0.9.5.94+bzr2803-0ubuntu1) ... Setting up python-pyatspi2 (2.1.91-0ubuntu1) ... Setting up simple-scan (3.1.91-0ubuntu1) ... Processing triggers for libc-bin ... ldconfig deferred processing now taking place Log ended: 2011-09-12 18:28:25 Now I can't install ubuntu-desktop because I can't install Unity because: The following packages have unmet dependencies: unity : Depends: compiz but it is not going to be installed Depends: compiz-core-abiversion-20110703 but it is not installable Depends: compiz-plugins-main-default but it is not going to be installed E: Unable to correct problems, you have held broken packages. ~$ sudo apt-get install compiz-core-abiversion Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package compiz-core-abiversion -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/847664 Title: dependency problem with virtual package compiz-core- abiversion-20110703 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/unity/+bug/847664/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs