Bonnie,
Thanks....that's what I thought - that since the BIN folder of my main project is more-or-less a snapshot of what the user's BIN folder will look like, adding all of them as a reference is the sure-fire way to make sure the latest versions exists in my development BIN folder.
Actually, part (not all, but part) of my problem was exactly what you mentioned at the end...I had 3 DLLs that were in my BIN folder but weren't explicitly referenced...and they only got there because I had manually copied them there.
So I've definitely learned something today (had to come across like an imbecile to get to that point, but hey, that's the price of progress).
Kevin