This problem went away after the following steps:
Booted into recovery, attempted to use the option to fix broken packages, fail to resolve archive.ubuntu.com, basically failed attempt at upgrading packages.
Boot into normal mode.
Open terminal as root, attempt apt-get upgrade (not distribution upgrade), installed whatever bits and pieces it needed, overwriting any older configs with package maintainer's versions.
Log out, no error but some terminal text, log in, log out, no error and also no funky text, just smoothly logs out to the login page.
This system is Mint 13 installed on USB with Cinnamon, now moved to MATE. After that I had the error text, and now after taking these above steps it hopefully will stay gone.