[Plugin: Contact Form 7] Arrows keep going round and round, but form submits

I have a contact form here: http://leightondesign.com/contact where the arrows keep going round and round after “Send” is clicked. The form does send the information, but there is never a confirmation message.

My client received 20+ of the same emails from his contact form, probably because the user had no way of knowing whether the form truly worked or not.

Never encountered this problem before.

http://wordpress.org/extend/plugins/contact-form-7/