Page loads fine for users but returns a 404 for Google & Moz

[leapSEO]

I have an e-commerce website that is built using Wordpress and the WP E-commerce plug-in, the products have always worked fine and the pages when you view them in a browser work fine and people can purchase the products with no problems.

However in the Google merchant feed and in the Moz crawl diagnostics certain product pages are returning a 404 error message and I can't work out why, especially as the pages load fine in the browser.

I had a look at the page headers and can see when the page does load the initial request does return a 404 error message, then every other request goes through and loads fine. Can anyone help me as to why this is happening?

A link to the product I have been using to test is: http://earthkindoriginals.co.uk/organic-clothing/lounge-wear/organic-tunic-top/

Here is a part of the header dump that I did:

http://earthkindoriginals.co.uk/organic-clothing/lounge-wear/organic-tunic-top/
 
GET /organic-clothing/lounge-wear/organic-tunic-top/ HTTP/1.1
Host: earthkindoriginals.co.uk
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:21.0) Gecko/20100101 Firefox/21.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8
Accept-Language: en-gb,en;q=0.5
Accept-Encoding: gzip, deflate
Cookie: __utma=159840937.1804930013.1369831087.1373619597.1373622660.4; __utmz=159840937.1369831087.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); wp-settings-1=imgsize%3Dmedium%26hidetb%3D1%26editor%3Dhtml%26urlbutton%3Dnone%26mfold%3Do%26align%3Dcenter%26ed_size%3D160%26libraryContent%3Dbrowse; wp-settings-time-1=1370438004; __utmb=159840937.3.10.1373622660; PHPSESSID=e6f3b379d54c1471a8c662bf52c24543; __utmc=159840937
Connection: keep-alive
 
HTTP/1.1 404 Not Found
Date: Fri, 12 Jul 2013 09:58:33 GMT
Server: Apache
X-Powered-By: PHP/5.2.17
X-Pingback: http://earthkindoriginals.co.uk/xmlrpc.php
Expires: Wed, 11 Jan 1984 05:00:00 GMT
Cache-Control: no-cache, must-revalidate, max-age=0
Pragma: no-cache
Vary: Accept-Encoding
Content-Encoding: gzip
Content-Length: 6653
Connection: close
Content-Type: text/html; charset=UTF-8

[leapSEO]

Thanks for the help guys, it is good to actually have a direction to look in now, I was just completely stuck before. I will post any updates I have.

[cahams]

Hello,

The status returned is 404 not found, this is independent of whether the page is loaded or not.

There is something that is generating that code either htaccess, some php code, maybe some redirection, a misconfigured rewrite, look for what can be, with that code, pages are not indexed.

Sorry for my english.

Best regards,
Carlos