During an upgrade from lucid (10.04) to precise (12.04), the X session froze, and I have been trying to recover the upgrade to get a stable system. I have performed the following steps:

1. Used ssh to log in to the stalled system over the network.
2. Checked the contents of the /var/log/dist-upgrade directory. There was no activity on main.log, apt.log or term.log.
3. top showed that process 'precise' was using about 3% CPU, but I could find no evidence that the upgrade process was still doing anything.
4. 'dpkg' did not show up in top, but it came up with pgrep dpkg | xargs ps
5. Killed the 'dpkg' and 'precise' processes
6. Tried to recover the upgrade by running sudo fuser -vki /var/lib/dpkg/lock;sudo dpkg --configure -a. This was partially successful (some packages were configured), but failed with the message Processing was halted because there were too many errors. I ran the same command a few times, and each time some packages were configured but others failed.
7. Tried running sudo apt-get -f install. It fails with similar errors to dpkg.

The current situation is that dpkg --configure -a and sudo apt-get -f install fails with two kinds of error:

1. Dependency issues, e.g.:

   dpkg: dependency problems prevent configuration of cifs-utils:
   cifs-utils depends on samba-common; however:
   Package samba-common is not configured yet.
   dpkg: error processing cifs-utils (--configure):
   dependency problems - leaving unconfigured
   

2. Resource conflict, e.g.:

   debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable
   

Additionally, it seems there's reference to potential boot problems, so I'm not keen to reboot without fixing the install first:

    dpkg: too many errors, stopping
    Processing triggers for initramfs-tools ...
    update-initramfs: Generating /boot/initrd.img-3.2.0-25-generic
    cryptsetup: WARNING: failed to detect canonical device of /dev/sda1
    cryptsetup: WARNING: could not determine root device from /etc/fstab

So my question is, how to get a working install when dpkg --configure -a fails?