Books Page?

Mooberry Book Manager uses the url http://www.{yoursite}.com/book/{book-title} for each of your books entered into the admin dashboard. Having a page that has the url http://www.{yoursite}.com/book is likely to cause problems, yes.

One thing you might try to resetting your permalinks. From your dashboard, go to Settings -> Permalinks and click the save button. You don’t need to make any changes. Simply saving the options on that screen will reset your permalinks.

I cannot advise further without seeing your website or knowing how it’s set up.

You can find documentation for Mooberry Book Manager on our website: http://www.mooberrybookmanager.com/.

Hope this helps!