$ERRORS[10] = __("Your version of MySQL is not currently supported. Please see 
                official site for more information.");
+
+       $ERRORS[11] = __("Sanity check request received twice. You could be running
+               Firebug or some other disrupting extension. Please turn it off.");
 ?>
 
 
 var caller_subop = false;
 
+var sanity_check_done = false;
+
 function expand_feed_callback() {
        if (xmlhttp.readyState == 4) {
                try {   
        if (xmlhttp.readyState == 4) {
 
                try {
-               
+
+                       if (sanity_check_done) {
+                               fatalError(11, "Sanity check request received twice. You could be running"+
+                             " Firebug or some other disrupting extension. Please turn it off.");
+                               return;
+                       }
+
                        if (!xmlhttp.responseXML) {
                                fatalError(3, "[D001, Received reply is not XML]: " + xmlhttp.responseText);
                                return;
                                }
                        }
 
+                       sanity_check_done = true;
+
                        init_second_stage();
 
                } catch (e) {
 
 var active_feed_id = 0;
 var active_feed_is_cat = false;
 var number_of_feeds = 0;
+var sanity_check_done = false;
 
 var xmlhttp = Ajax.getTransport();
 var xmlhttp_ctr = Ajax.getTransport();
        if (xmlhttp.readyState == 4) {
 
                try {
-               
+       
+                       if (sanity_check_done) {
+                               fatalError(11, "Sanity check request received twice. You could be running"+
+                             " Firebug or some other disrupting extension. Please turn it off.");
+                               return;
+                       }
+
                        if (!xmlhttp.responseXML) {
                                fatalError(3, "[D001, Received reply is not XML]: " + xmlhttp.responseText);
                                return;
                                }
                        }
 
+                       sanity_check_done = true;
+
                        init_second_stage();
 
                } catch (e) {