I just downloaded samples of
Summer Lightning and
Blandings Castle and get the same error you do on both. My guess would be that the publisher,
W.W. Norton, or their conversion sub-contractor did something that screwed up the encoding so that the Kindle thinks it's in a different language than it is.
Contacting Kindle Support and perhaps contacting the publisher who has an eBook help form at
http://books.wwnorton.com/books/help...aspx?tid=10047 might get them to get things fixed so that an updated Kindle version can be downloaded.