It is connected as a storage device for my Wii. That area is full of different electronics because the Wii is smack dab in the middle of my home media center. I've been talking to other folks about the possibility that the Wii did this but their response is the same, they've never heard of or seen anything like this happen before.
This HD is in a pretty decent enclosure. At this point in time I suspect the Wii had to have something to do with it, but given nobody else shares that opinion and my knowledge of the Wii is so basic and limited, its not much of a theory. Three of these folks are moderators on Wii forums who have pretty much seen it all. Not very reassuring

.
EDIT
It is worth adding that the Wii generally only reads from the HD. Last night I was playing a game on an NES Emulator and attempted to make a Save State, which would write to the HD. The drive had been performing without issue all day long. Though attempting to create Save States had been causing the Wii to freeze, requiring a hard reset. When it died I was attempting to create a Save State.
I received an error saying it could not write to the HD, followed by an error it could not find the directory (dir listing, for me to select a new location to create a save state). I then hopped out of the emu, and nothing else was working, as if the drive had been disconnected. I took it to Windows and was greeted with the screenshot provided in my first post.
Note that the freezing while creating a save state is a known issue with the emulator. It is recommended you have an SD card inserted and that save states be stored there, not on the HD. This would have fixed my freezing issue, but I didn't learn this was a known problem until after this fiasco began. Considering the only write to the HD happened during the save state, I have a hard time dismissing that as the culprit.
Either way there is no fix or remedy. What happened, happened. My only concern now is whether the drive needs to be tossed into the garbage or whether I want to assume the save state was the source of the problem and the HD is in fact safe to store data on. I hate to throw it away, especially when I cannot find any problems with it through testing.