Those lines may save your life whenever you use the advanced_forum module.

advanced-forum-is-stupid.php

/**
 * Implements hook_process().
 */
function MYTHEMEORMODULE_process(&$variables, $hook) {
  // Seems legit.
  // @see laborange2_theme_registry_alter().
  if (false === strpos($hook, 'advanced_forum')) {
    // This one is a stupid variable mis-use and typo from advanced_forum.
    if (!empty($variables['theme_hook_suggestion']) && false !== strpos($variables['theme_hook_suggestion'], 'advanced_forum')) {
      // Do not override the 'theme_hook_suggestion' other than advanced
      // forums ones, because using theme(ARRAY_OF_HOOKS) actually uses
      // it legitimately (or not).
      unset($variables['theme_hook_suggestion']);
    }
    // And this one is because advanced_forum templates are stupid too.
    if (!empty($variables['theme_hook_suggestions'])) {
      foreach ($variables['theme_hook_suggestions'] as $i => $value) {
        if ('a' === $value[0] && 0 === strpos($value, 'advanced_forum')) {
          unset($variables['theme_hook_suggestions'][$i]);
        }
      }
    }
  }
}

/**
 * Implements hook_theme_registry_alter().
 */
function MYTHEMEORMODULE_theme_registry_alter(&$theme_registry) {
  // Seems legit too.
  // @see MYTHEMEORMODULE_process().
  foreach (array('node', 'comment') as $key) {
    if (isset($theme_registry[$key]['preprocess functions'])) {
      foreach ($theme_registry[$key]['preprocess functions'] as $i => $value) {
        if ('a' === $value[0] && 0 === strpos($value, 'advanced_forum')) {
          unset($theme_registry[$key]['preprocess functions'][$i]);
        }
      }
    }
  }
}