After solving all my mount problems and changing from dynamic to static addressing by editing /etc/network/interfaces, I reboot the system and was greeted with:
Welcome to emergency mode. "systemctl default", "systemctl reboot" to try again, or press Control-D to continue: That's a mild paraphrase, as I can't ssh in so I can't clip from the screen. I entered the system's root password and got a root prompt, just spent three hours Googling a solution, didn't find any I could either make sense of or use, and am now asking here. If it's easier to re-install, that's quite all right, as I haven't done anything on the system I can't redo quickly and easily. If a I re-install, should I use the updated DVD disk 1 instead of the original one? This is being made all the harder because for some reason the audio level of the main system audio output has dropped by 20dB after the reboot, and amixer says everything's up full.