Google Webmaster Tools 404 error anomally

Any clue as to why I get reports from Google webmaster tools for a 404 error that has

pointing to
testimonials/www.prolongroofcare.com/testimonials
This link does not appear in the page source of the offending page. Only thing I can imagine is it is getting formed by php commands on the server side at some point or via apache mod-rewrite rules but I have no idea how to trace it. Any help would be much appreciated. thanks in advance.

In your header of your page’s HTML source, you have this:

<link rel="canonical" href="www.prolongroofcare.com/testimonials/index.php" />

You need a http:// in that URL. Without the http, the browser is treating it as a relative URL, rather than an absolute URL.

So actually, the browser thinks the URL is this:

And that returns a 404 page.

Thank you so much.