Well, here’s how the story of picking up Conficker at the library played out:
Yes, thank you so much! Everything you said was true. Apparently someone’s USB drive was infected and infected many computers here. We are very appreciative for your technological detective work. The head of IT was very incredulous because everything is deep frozen after it is shut down. But it was all true and I am very grateful
The part about “many computers here” seems worrisome; they’re apparently not running any defensive software at all.