Dear Jim. I would start all over. Make sure that you install all the programs in the installer. At one point in the installer it asks you to install the Mint specific programs. If that is all done, you can safely reboot.
I don't know what happened, but it's difficult to help you like this. It's better to have a fresh start. It's worth it!
Okay, I'm back to my original state after asking the local geek what I could do without hitting the Debian installer CD for hours and hours and he told me to go into Sessions in the green log-in screen and hit "Failsafe terminal" and type your mint installer sequence there, and once I got back I hit the Synaptic Manager which filtered out that "xserver-xorg-core" librecode0 was broken and erased it, then I did another mint-install to replace the broken file, but though we're back up, still the same problems as before, like black to Lightweight screen and no Update Manager, etc. Does that mean doing the whole Debian CD install all over again or can it be done thru mint installs?