Just remove the register="0" attribute from the Level 1 pro-form shortcode. If you look at the shortcode the Level 1 pro-form generator outputs, you'll notice that attribute isn't there, it's just for the free registration pro-form.
[s2Member-Pro-PayPal-Form level="1" ccaps="" desc="$10 USD / Monthly ( recurring charge, for ongoing access )" ps="paypal" lc="" cc="USD" dg="0" ns="1" custom="dev31.visualmediahosting.com" ta="0" tp="0" tt="M" ra="10" rp="1" rt="M" rr="1" rrt="" rra="2" accept="paypal,visa,mastercard,amex,discover,maestro,solo" accept_via_paypal="paypal" coupon="" accept_coupons="0" default_country_code="" captcha="0" /]
Let me know if that solves the problem.
I hope it helps.