After a few searches, I figured out that the FDD may be the problem.

Unplug it, plug back in everything else, flip the switch...

BEWM! Welcome to Macintosh

So how do I fix my FDD's troubles? On boot the inner head would repeatedly engage and disengage (clicking noise). Or is this perhaps the start of a faulty power supply? (Mac resets because it can't put out enough current to power everything?)

Also, it seems that my wavy screen edges have returned. Outside of that everything is fine.