Good morning!
Please change the name of the GET parameter _wpcf7_request_ver to _wpcf7_req_ver or something
?_wpcf7_is_ajax_call=1&_wpcf7=215&_wpcf7_request_ver=1375403481714
Better WP Security and other plugins and sane .htaccess rules block requests having "request" in the query string
Thank you!
Viktor Szépe