Originally Posted by Zuzana Miguel

.htaccess:

RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} ^www\.(.*)$ [NC]
RewriteRule ^(.*)$ http://%1/$1 [R=301,L]


This will make whatever comes from Domain Name Registration and Web Hosting | Domain.com , go to: domain.com (without www)

Probably updating your permalinks will help... Just go to the page, and click Save.