--- C:\www\sites\all\modules\fb\fb.module 
+++ ftp://Gradspot/sites/all/modules/fb/fb.module 
@@ -255,8 +255,14 @@
     $action .= '&' . implode('&', $parts);
   }
 
+  //if $action starts with a /, we need to remove it, otherwise url() returns
+  //http://example.com//path/to/action
+  if(substr($action, 0, 1) == '/') {
+    $action = substr($action, 1);
+  }
+  
   //drupal_set_message("form action now " . "http://".$_SERVER['HTTP_HOST']. $action); // debug
-  return "http://".$_SERVER['HTTP_HOST']. $action;
+  return url($action, NULL, NULL, TRUE);
 }
 
 function _fb_handling_form() {