If you use htm or html pages that contain xml coding you will need to add a .htaccess file to your site to parse and display them correctly.
So if your page contains the following you will need to setup an .htaccess file:
Create a file named .htaccess and add the following on one line in that file:
Save the file as .htaccess and upload to the directory you have the xml pages in.
Your xml pages will now work correctly.