>deleting ^Accept$ in BOTH Custom User Fields (one for the Adult Acceptance and Age Verification), and the other Custom User Field (for the Birthday Entry)
The RegEx should have never been set in the birthday profile field. That's why i wanted to see its settings before. It explains why this field was throwing an unusual error during registration. The RegEx should only be set in the custom text profile field where you want to require the word 'Accept'. With your current settings, users can enter anything they want and you have to manually approve it. You will have less work activating and communicating with new users by just getting the RegEx to work. Only add it to your acceptance profile field.
Also, you should still set both profile fields to be editable by "Owner during registration and Administrator" as this had probably nothing to do with the issues preventing you from submitting the registration form and prevents users from changing the fields value afterwards.