Prosperity, the Tinderbook, had been acting badly for two weeks before the trip. Before leaving, I decided I'd better get a new hard disk, and opted to have a pro come and install the thing.
Unfortunately, this particular professional thought that drag-copying a disk in Finder was a good way to proceed with replacing the system disk. That turns out not to be the case. I was at the office at 1am fixing the disk, with a taxi to the airport slated for 6.
And I'm still finding problems with permissions, everywhere. I'd have spent less time doing the whole thing myself, and saved a few hundred bucks.