Actually, I don’t know how I killed it, but it’s definitely dead. (This is not one of those no-moving-parts “drives” that uses flash memory; this is a real spinning drive, albeit teensy.) [Warning: linked site may emit horrid noises.]
Maybe I just had too much activity going at once. I was processing a stack of forty, fifty MP3 files, which I was going to copy to another machine not on my network, and both the application and the Explorer window crapped out on me, more or less simultaneously. The application is intact, but the drive is now considered to be diskless: it’s recognized as a drive, but any attempt to use a disk utility is met with “No disk in drive J:” and/or “Please insert disk into drive J:”, neither of which is exactly practicable.
I dashed off a tech-support request, which I expect will be answered, if it’s answered at all, with “Bury it, deep.”