package man-db 2.5.5-1build1 failed to install/upgrade: package man-db is already installed and configured

Your sound problems have nothing to do with the failure logs attached to this bug report. I suggest asking a separate question about your sound problems: https://answers.launchpad.net/ubuntu might be a good place.

As for the failure logs attached to this bug, we keep getting this kind of "already installed and configured" error and it doesn't make a lot of sense to me. It's not a bug in man-db; maybe it's update-manager's fault for incorrectly using 'dpkg --configure'? Reassigning there in case Michael has some insight.

Thanks for your bugreport.

I looked into this and I think I can reproduce it now. It appears to be a problem with the way apt handles packages in state "triggers-pending". To reproduce:
$ sudo dpkg -i --no-triggers 2vcard
$ sudo apt-get install --reinstall 2vcard

This bug was fixed in the package apt - 0.7.23.1ubuntu1

---------------
apt (0.7.23.1ubuntu1) karmic; urgency=low

  [ Matt Zimmerman ]
  * apt-pkg/deb/dpkgpm.cc:
    - Suppress apport reports on dpkg short reads (these I/O errors are not
      generally indicative of a bug in the packaging)

  [ Loïc Minier ]
  * cmdline/apt-key:
    - Emit a warning if removed keys keyring is missing and skip associated
      checks (LP: #218971)

  [ Brian Murray ]
  * cmdline/apt-get.cc:
    - typo fix (LP: #370094)

  [ Michael Vogt ]
  * apt-pkg/deb/dpkgpm.cc:
    - when tcgetattr() returns non-zero skip all pty magic
      (thanks to Simon Richter, closes: #509866)
  * apt-inst/contrib/arfile.cc:
    - show propper error message for Invalid archive members
  * apt-pkg/acquire-worker.cc:
    - show error details of failed methods
  * apt-pkg/contrib/fileutl.cc:
    - if a process aborts with signal, show signal number
  * methods/http.cc:
    - ignore SIGPIPE, we deal with EPIPE from write in
      HttpMethod::ServerDie() (LP: #385144)
  * debian/apt.cron.daily:
    - if the timestamp is too far in the future, delete it
      (LP: #135262)

  [ Merge ]
  * merged from debian, reverted the libdlopen-udev branch
    because its too late in the release process for this now
  * not merged the proxy behaviour change from 0.7.23 (that will
    be part of lucid)

apt (0.7.23.1) unstable; urgency=low

  [ Michael Vogt ]
  * apt-pkg/pkgcache.cc:
    - do not set internel "needs-configure" state for packages in
      triggers-pending state. dpkg will deal with the trigger and
      it if does it before we trigger it, dpkg will error out
      (LP: #414631)
  * apt-pkg/acquire-item.cc:
    - do not segfault on invalid items (closes: #544080)

apt (0.7.23) unstable; urgency=low

  [ David Kalnischkies ]
  * cmdline/apt-get.cc:
    - add APT::Get::HideAutoRemove=small to display only a short line
      instead of the full package list. (Closes: #537450)
    - ShowBroken() in build-dep (by Mike O'Connor, Closes: #145916)
    - check for statfs.f_type (by Robert Millan, Closes: #509313)
    - correct the order of picked package binary vs source in source
    - use SourceVersion instead of the BinaryVersion to get the source
      Patch by Matt Kraai, thanks! (Closes: #382826)
    - add pkg/archive and codename in source (Closes: #414105, #441178)
  * apt-pkg/contrib/strutl.cc:
    - enable thousand separator according to the current locale
      (by Luca Bruno, Closes: #223712)
  * doc/apt.conf.5.xml:
    - mention the apt.conf.d dir (by Vincent McIntyre, Closes: #520831)
  * apt-inst/contrib/arfile.cc:
    - use sizeof instead strlen (by Marius Vollmer, Closes: #504325)
  * doc/apt-mark.8.xml:
    - improve manpage based on patch by Carl Chenet (Closes: #510286)
  * apt-pkg/acquire-item.cc:
    - use configsettings for dynamic compression type use and order.
      Based on a patch by Jyrki Muukkonen, thanks! (LP: #71746)
  * apt-pkg/aptconfiguration.cc:
    - add default configuration for compression types and add lzma
      support. Order is now bzip2, lzma, gzip, none (Closes: #510526)
  * ftparchive/writer.cc:
    - add lzma support also here, patch for this (and...