I have installed a website for somebody a few months ago. Until the last week he never had problems. Since last week, the site isn't accessible anymore through Firefox (IE works without errors).
XML Parsing Error: XML or text declaration not at start of entity
Line Number 112, Column 1:
<?xml version="1.0" encoding="UTF-8"?>
He has no idea how to change templates or other important stuff on the page. He only knows how to change pages through the backend or to upload images through FTP. And that is the only thing he did last week. And i have nothing changed...