I've been using Pro Sites for awhile now, but I just ran

I've been using Pro Sites for awhile now, but I just ran a test sign-up today, and it won't let me past the page where I select a plan!
I can click on the plan that I want, but as soon as I click the paypal button to checkout, it tells me "Please choose your desired level and payment plan.".
Was there something in the last update that could have caused that problem?
Help! No one can sign-up on my site right now!