Apache error log:

[Thu Jun 18 11:11:47 1998] Possible PHP3 memory leak detected
 (harmless):  12 bytes from language-parser.y:637

This may be related to spurious and intermittent parse errors with:

function lookup($domain, $root) {
        exec("../../../cgi-bin/ns.cgi \"$domain\" \"$root\"", $result, $ret);
        //$strresult = $result[0]."\n".$result[1];
        //for($i=0;$i<count($result);$i++) strresult .= $result[$i];
        $strresult = "";
        //for($i=0;$i<2;$i++) strresult .= $result[$i];

        switch ($ret) {
        case 0:
                display($domain, $root, "A");
                break;
        case 1:
                display($domain, $root, "U", $strresult);
                break;
        case 2:
                display($domain, $root, "E", $strresult);
                break;
        default:
                errorpage("Uncased return \"$ret\" in lookup()");
        }
}

The parse errors are on the line:
       $strresult = "";