Thanks for the tips, i still can´t fix this and can´t reproduce the problem. But i get everyday 2 or 3 clients with this problem. I don´t know when does it happen, have clients with IE, firefox, chrome and opera (win xp, 7, vista) add in his baskets different products and same problem. People make this steps. 1 - Add a product 2- register an account 3- Try to add a shipping address and here they stuck,they can´t add a new address. 4- back to step 1, trying to continue with the wrong shipping address and they can´t...continue button don´t work and no error was shown. Generally they leave the site and never come back, in some cases they call us or send an email.