Is this the plugin you are referring to?
https://wordpress.org/plugins/wp-about-author/
If you are then you may have better luck posting in that plugin's dedicated support sub-forum.
http://wordpress.org/support/plugin/wp-about-author#postform
But before you create another topic can you switch to the Twenty Fourteen theme, deactivate all of your plugins except the WP Author and Shareholic plugin and see if that behavior still happens?
I want to rule out it possibly being an issue with your theme.