Error: An illegal choice has been detected

I created what I thought to be a fairly simple view with this module to give a quick list of new user signups in a date range and, while it works, every time I load the view, I get "An illegal choice has been detected. Please contact the site administrator." Can't figure out what it might be since the error isn't very descriptive.

Here's the export from views:

$view = new view;
$view->name = 'signup_report';
$view->description = '';
$view->tag = '';
$view->view_php = '';
$view->base_table = 'users';
$view->is_cacheable = FALSE;
$view->api_version = 2;
$view->disabled = FALSE; /* Edit this to true to make a default view disabled initially */
$handler = $view->new_display('default', 'Defaults', 'default');
$handler->override_option('fields', array(
  'created' => array(
    'label' => 'Created date',
    'alter' => array(
      'alter_text' => 0,
      'text' => '',
      'make_link' => 0,
      'path' => '',
      'link_class' => '',
      'alt' => '',
      'prefix' => '',
      'suffix' => '',
      'help' => '',
      'trim' => 0,
      'max_length' => '',
      'word_boundary' => 1,
      'ellipsis' => 1,
      'strip_tags' => 0,
      'html' => 0,
    ),
    'date_format' => 'small',
    'custom_date_format' => 'm/d/Y',
    'exclude' => 0,
    'id' => 'created',
    'table' => 'users',
    'field' => 'created',
    'relationship' => 'none',
  ),
  'name' => array(
    'label' => 'Name',
    'alter' => array(
      'alter_text' => 0,
      'text' => '',
      'make_link' => 0,
      'path' => '',
      'link_class' => '',
      'alt' => '',
      'prefix' => '',
      'suffix' => '',
      'help' => '',
      'trim' => 0,
      'max_length' => '',
      'word_boundary' => 1,
      'ellipsis' => 1,
      'strip_tags' => 0,
      'html' => 0,
    ),
    'link_to_user' => 1,
    'overwrite_anonymous' => 0,
    'anonymous_text' => '',
    'exclude' => 0,
    'id' => 'name',
    'table' => 'users',
    'field' => 'name',
    'relationship' => 'none',
  ),
  'mail' => array(
    'label' => 'E-mail',
    'alter' => array(
      'alter_text' => 0,
      'text' => '',
      'make_link' => 0,
      'path' => '',
      'link_class' => '',
      'alt' => '',
      'prefix' => '',
      'suffix' => '',
      'help' => '',
      'trim' => 0,
      'max_length' => '',
      'word_boundary' => 1,
      'ellipsis' => 1,
      'strip_tags' => 0,
      'html' => 0,
    ),
    'link_to_user' => '0',
    'exclude' => 0,
    'id' => 'mail',
    'table' => 'users',
    'field' => 'mail',
    'override' => array(
      'button' => 'Override',
    ),
    'relationship' => 'none',
  ),
  'rid' => array(
    'label' => 'Roles',
    'alter' => array(
      'alter_text' => 0,
      'text' => '',
      'make_link' => 0,
      'path' => '',
      'link_class' => '',
      'alt' => '',
      'prefix' => '',
      'suffix' => '',
      'help' => '',
      'trim' => 0,
      'max_length' => '',
      'word_boundary' => 1,
      'ellipsis' => 1,
      'strip_tags' => 0,
      'html' => 0,
    ),
    'type' => 'separator',
    'separator' => ', ',
    'empty' => '',
    'exclude' => 0,
    'id' => 'rid',
    'table' => 'users_roles',
    'field' => 'rid',
    'relationship' => 'none',
  ),
));
$handler->override_option('filters', array(
  'date_filter' => array(
    'operator' => 'between',
    'value' => array(
      'value' => NULL,
      'min' => NULL,
      'max' => NULL,
      'default_date' => 'now',
      'default_to_date' => 'now',
    ),
    'group' => '0',
    'exposed' => TRUE,
    'expose' => array(
      'use_operator' => 0,
      'operator' => 'date_filter_op',
      'identifier' => 'date_filter',
      'label' => 'Date Range',
      'optional' => 0,
      'remember' => 1,
    ),
    'date_fields' => array(
      'users.created' => 'users.created',
    ),
    'date_method' => 'OR',
    'granularity' => 'day',
    'form_type' => 'date_select',
    'default_date' => 'now',
    'default_to_date' => 'now',
    'year_range' => '-10:+0',
    'id' => 'date_filter',
    'table' => 'users',
    'field' => 'date_filter',
    'relationship' => 'none',
    'override' => array(
      'button' => 'Override',
    ),
  ),
));
$handler->override_option('access', array(
  'type' => 'role',
  'role' => array(
    '3' => 3,
  ),
));
$handler->override_option('cache', array(
  'type' => 'none',
));
$handler->override_option('title', 'Signups Report');
$handler->override_option('items_per_page', 0);
$handler->override_option('style_plugin', 'views_calc');
$handler->override_option('style_options', array(
  'grouping' => '',
  'override' => 1,
  'sticky' => 0,
  'order' => 'desc',
  'columns' => array(
    'created' => 'created',
    'name' => 'name',
    'mail' => 'mail',
    'rid' => 'rid',
  ),
  'info' => array(
    'created' => array(
      'sortable' => 0,
      'separator' => '',
      'justification' => 'views_calc_justify_none',
      'has_calc' => 0,
      'calc' => array(
        'COUNT' => 'COUNT',
      ),
    ),
    'name' => array(
      'sortable' => 0,
      'separator' => '',
      'justification' => 'views_calc_justify_none',
      'has_calc' => 1,
      'calc' => array(
        'COUNT' => 'COUNT',
      ),
    ),
    'mail' => array(
      'sortable' => 0,
      'separator' => '',
      'justification' => 'views_calc_justify_none',
      'has_calc' => 0,
      'calc' => array(),
    ),
    'rid' => array(
      'separator' => '',
      'justification' => 'views_calc_justify_none',
      'has_calc' => 1,
      'calc' => array(
        'COUNT' => 'COUNT',
      ),
    ),
  ),
  'default' => 'created',
  'detailed_values' => '0',
));
$handler = $view->new_display('page', 'List Page', 'page_1');
$handler->override_option('path', 'signups');
$handler->override_option('menu', array(
  'type' => 'normal',
  'title' => 'Signups Report',
  'description' => '',
  'weight' => '0',
  'name' => 'navigation',
));
$handler->override_option('tab_options', array(
  'type' => 'none',
  'title' => '',
  'description' => '',
  'weight' => 0,
));