Problem with woocommerce (checkout)

Hi
I have a problem with my woocommerce, the problem is in the checkout page.
I choosed that everyone can buy on my website so you dont need to be a registered user but there is a problem:
if a costumer (no registered user) enter on my website and choose a product and after clicks on “checkout” he go in the multi-step and remain frozen in the login page. The next step would be “billing information” but the customer remains frozen in the login voice of the multistep. on this page there ‘no message type
only a blank page
what i have to do for to solve this problem?

thank you

i put an image so you can see what i mean
http://i42.tinypic.com/14io50h.png