Index: thickbox/thickbox.module
===================================================================
--- thickbox/thickbox.module	(revision 1107)
+++ thickbox/thickbox.module	(working copy)
@@ -128,6 +128,7 @@
   }
 
   if (variable_get('thickbox_auto', 0) && module_exists('image')) {
+    drupal_add_js("var base_path = ". drupal_to_js(base_path()) .";", 'inline');
     drupal_add_js("var thickbox_derivative = ". drupal_to_js(variable_get('thickbox_derivative', 'preview')) .";", 'inline');
     drupal_add_js($path .'/thickbox_auto.js');
   }
Index: thickbox/thickbox_auto.js
===================================================================
--- thickbox/thickbox_auto.js	(revision 1107)
+++ thickbox/thickbox_auto.js	(working copy)
@@ -38,11 +38,11 @@
      * the script should allways use the original picture ("true || ").
      */
     if (thickbox_derivative == "original") {
-      var href = img.attr("src").replace(".thumbnail", "");
+    	thickbox_derivative = "_original";
     }
-    else {
-      var href = img.attr("src").replace(".thumbnail", "." + thickbox_derivative);
-    }
+    
+    var original_href = $(this).attr("href").replace(new RegExp('^' + base_path + '(node/)?'), "");
+    var href = base_path + "image/view/" + encodeURIComponent(original_href) + "/" + thickbox_derivative + "/image.jpg";
 
     // Finally rewrite the link and wait for thickbox.js to apply the effects.
     $(this).attr({href: href, title: title, rel: group});
Index: image/image.module
===================================================================
--- image/image.module	(revision 1105)
+++ image/image.module	(working copy)
@@ -804,6 +804,16 @@
   }
 
   if (isset($nid)) {
+    if (!is_numeric($nid)) {
+      $path = drupal_get_normal_path(urldecode($nid));
+      if (strpos($path, 'node/') === 0) {
+        $nid = substr($path, 5);
+      }
+      else {
+      	return drupal_not_found();
+      }
+    }
+
     $node = node_load(array('type' => 'image', 'nid' => $nid));
     if ($node) {
       if (!node_access('view', $node)) {