Body class name has an ampersand
It's not a D7 bug - all core code uses drupal_html_class(), which removes any dodgy characters (including ampersands) by running the incoming string through drupal_clean_css_identifier(). 

Presumably your theme (or a custom/contrib module) is adding a class without sanitising it. Look for something like:

function MYTHEME_preprocess_html(&amp;$vars) {
  if ($node = menu_get_object()) {
    $vars['classes_array'][] = str_replace(' ', '-', $node-&gt;title);
  }
}


and change it to use

$vars['classes_array'][] = drupal_html_class($node-&gt;title);