File upload ajax and Radio Buttons not cooperating in registration form
If I understand you right you'll need to write a small custom module to hook into the registration form using hook_form_alter(), and add the #limit_validation_errors property to the correct radio group. This should stop the validation from running on AJAX calls, but still let it run when the form is submitted.

The code might look something like this:

function MYMODULE_form_user_register_form_alter(&amp;$form, &amp;$form_state, $form_id) {
  $form['radio_button']['#limit_validation_errors'] = array();
}


It's quite likely that the particular radio group you're after will be buried in the nested $form array somewhere so you'll probably need to use the dpm() function (part of of the Devel module) to inspect the form and determine the correct element to alter.