I'm running Calibre on OSX Lion. I downloaded
http://www.gutenberg.org/ebooks/62 in both .epub versions and tried to add it several different ways to Calibre.
calibre, version 0.8.37
ERROR: Adding failed: The add books process seems to have hung. Try restarting calibre and adding the books in smaller increments, until you find the problem book.
What's my next step?