Well, it seems I've finally experienced my first memory card death. One of my two Gamecube memory cards decided to up and die due to months of neglect, I guess. Or perhaps it got screwed up when I used it with the Wii for getting some extra stuff (although I didn't notice any such thing) in Radiant Dawn, which was the last time that it had been used. Fortunately, most of my significant data saves were on the other memory card, but it'll be a pain to play Path of Radiance all over again.
I'm mostly bummed by the fact that, of course, this happened for some unknown reason rather than because of some error on my part. (And, at least on my end, if something could last forever I'd have more faith in myself about accomplishing just that.) At least then I wouldn't have to ask, "why?" Otherwise it's irritatingly stupid.