When running this IP the Lookup function never returns. This is the only IP I have seen thus far that has this issue.

$whois = new Whois();
$result = $whois->Lookup('46.4.169.96');
print_r($result);

From what I can tell it keep looping / recursing and never meets the final condition. I didn't have time to debug more but seems be a bug in:

parse_results() which then calls
$this->Process($rwdata)

The call to process never returns. There is some dynamic loading which is quite difficult to trace.