Problem with new user registration – redirect to designated register page not working

I’m still having the following issue with registration:

After the member fills in the first username/email/password form I just get a popup window empty apart from the message:

“You currently have a subscription for the Exclusive members area subscription. If you wish to sign up a different subscription then you can do below.”

I only have one subscription plan, which is free.

How can i either direct users to the Members landing page or give them a button to click to send them there?

This is now becoming quite an urgent matter so any help gratefully received.