JeeDieRay on "[Theme: WP Opulus] permalinks"

Hello!

When I change the permalinks, the links in the main navigation menu will not work anymore:

• Post name http://thymic-carcinoma.com/sample-post/
• Custom Structure http://thymic-carcinoma.com/%postname%/

Error returned:
" Error occurred: 404 - not found
Apache Server

Does the theme overrule the permalinks settings somewhere?

Thanks!