There does seem to be a problem with a number of books in that catalog. Looking at the ePubs themselves, they do have some structural problems which might be confusing Stanza's import process (the first one I notice is that the "mimetype" entry is supposed to be stored uncompressed, but in those files it is being compressed). Could you contact the catalog provider and let them know about the issue, and ask them to contact us directly if they want to discuss ways to improve the compatibility between their books and Stanza?