thanks, ixtab for being so patient for me. I went to the collections manager thread, re-downloaded the kindlet and developer's certificate zip files, and installed them, and now things are working back the way they should. I was concerned for a bit.
(you have no idea the courage it's taking me to do this stuff - I really don't know what I'm doing, so am following directions blindly, and am rather impressed with myself that I actually get them to work. Maybe I'll try the margins hack next?)