GD Star Rating – AJAX XSS Error

Hi there,
since a few days my GD Star Rating not work anymore.
When someone click on the stars to rate, only the “please wait…” spinner was displayed and no more, the vote will not saved.

I’ve found this Ajax Request in the console log:
http://www.my-domain.net/wp-content/plugins/gd-star-rating/ajax.php?_ajax_nonce=e719cd0016&vote_id=289&vote_value=5&vote_type=a&vote_tpl=10&vote_size=20

it responds only “xss_error”, but why?

I think this is the error, but why it responds “xss_error”, a few days ago it has worked fine.

http://wordpress.org/extend/plugins/gd-star-rating/