I have succeeded in making my system all but useless over PLC!

Wait...

Actually, this is sort of a good thing in that I believe the cause was a pair of failing UPS units plus one bad power strip. One of the UPS units may have improved things by filtering some noise, but when removed things got bad.
Basically, I have one UPS and power strip for my TV/stereo. I had the battery backup for the TV and DTV receiver such that if power went out for a short time or flickered, the TV would continue to work and the DTV DVR would not reset. I noticed that the lights and TV flickering at the same time...meaning the TV power was not being filtered by the UPS correctly. I unplugged the UPS and the TV and DTV DVR immediately died. Hmmm, turns out it was probably overloaded (350VA UPS isn't quite big enough I guess) and the battery is toast. I'll check the power strip too, but I think the UPS is the main issue.
Secondly, the UPS I was using for my office was WELL undersized and the battery was very much TOAST! I installed a 1500VA unit and it works great.
Third, I know I have a power strip on a TV/console setup that's causing noise/signal sucking issues. I haven't replaced it yet, but if I plug anything in on that circuit, it does not work.
So, after pulling the 2 UPS units and installing the one in the office, things work HORRIBLY! This means that I'll need to finish that filter project I've got 50% done and sitting in the basement. It also means I'll need to obtain a battery for the bad UPS and up to 3 good quality surge protectors. I may also opt to purchase a filter (or a few). I just need to verify that I'm well under the 5A limit for the X10 plugin filters.