Pro Sites: Sign Up's Failing

This all worked before but now it's not. I don't know if it's due to an update.

New site sign ups are failing and I'm not sure where to start troubleshooting this. I'm running the latest prosites with paypal pro.

A new user comes in signs up, goes to the next page for the site title, human verification etc. I check "I'm interested" for the upgrade and continue. It takes me next to the 'Congratulations your new site..." page and doesn't go to the upgrade page. No emails are sent out to the new user or to the admin. A site is not created nor is a user created. Nothing happens!

I can send emails to users from the admin backend.

Help!