Josephiah:
(Another possible symptom: with just the board plugged in on its own, the TX light is now staying lit solidly except for when trying to load something, which is a bit weird. In normal operation of my setup I expect TX to flicker in response to inputs on A0-A7, and otherwise to remain off. Grounding the analog inputs makes TX go off. So there's some kind of unwanted interaction happening in there somewhere. Sigh)
Unpredictable results are normal when reading from floating pins.