Checkout.js disables continue conflicts with autocomplete

You can test on http://krinkel.mallezie.kiplin-drupal01.chiro.be/krinkel-2013
If You choose one of the product's, you enter a registration form. (From entity_registration / Commerce_registration module).
There you have a field 'Groep' or 'Ploeg' (dependant on your first choice) where you can select an entity reference (type 'sche' for example, that generates results). Making a choice, with the arrows, and pressing enter, blocks the 'continue' button. (At lesast tested in chromium and firefox).

I found some sort of solution with following javascript code.

(function($) {

/**
 * Disable the continue buttons in the checkout process once they are clicked
 * and provide a notification to the user.
 */
Drupal.behaviors.commerceCheckout = {
  attach: function (context, settings) {
    $('input.form-autocomplete').keypress(function(e){
        var code = e.keyCode || e.which;
        if( code === 13 ) {
            e.preventDefault();
        }
    });
    // When the buttons to move from page to page in the checkout process are
    // clicked we disable them so they are not accidently clicked twice.
    $('input.checkout-continue:not(.checkout-processed)', context).addClass('checkout-processed').click(function() {
      var $this = $(this);
      $this.clone().insertAfter(this).attr('disabled', true).next().removeClass('element-invisible');
      $this.hide();
    });
  }
}

})(jQuery);

I found some information on following links:
http://stackoverflow.com/questions/12325066/button-click-event-fires-whe...
http://stackoverflow.com/questions/4763638/enter-triggers-button-click/4...

It seems that perhaps disabling the button as submit button should do the trick.

Also noticed that hitting the enter key on a select-element doesn't trigger the click event. Neither when hitting enter in a text-area.