IE and CSS with HTTPS

Hi,

I have an issue with Secure Pages. CSS doesn't load in https pages, only with IE.
I tried patches I found, like :

securepages.module :

  function securepages_boot() {
-    global $base_url;
     $path = isset($_GET['q']) ? $_GET['q'] : '';


  function securepages_redirect() {
+   global $base_url;
     $path = isset($_GET['q']) ? $_GET['q'] : '';
     $page_match = securepages_match($path);

or

settings.php :

if (!empty($_SERVER['HTTPS'])) {
    $base_url = 'https://' . $_SERVER['HTTP_HOST'];
}

or

bootstrap.inc :
   function drupal_page_header() {
     header("Expires: Sun, 19 Nov 1978 05:00:00 GMT");
     header("Last-Modified: ". gmdate("D, d M Y H:i:s") ." GMT");
-    header("Cache-Control: store, no-cache, must-revalidate");
+    header("Cache-Control: no-store, no-cache, must-revalidate");

But it still doesn't work. Any idea ?
Thx.