SEO url error

Hi,

I have followed the instructions provided here, http://www.askabouthugo.com/all-about-p ... -htaccess/ on how to set seo urls.

However i have a problem, because i get this message when i click on any product.

Not Found

The requested URL /xxxx/xxxx was not found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

SInce the urls have become friendly, but there is always this error saying that url was not found. I have already entered the products before i have modified htaccess file and other settings.

any ideas?

Thanks