The variable $nospamnumber is basically which NoSpam! question it is so that the hack can determine which answer it should be comparing the input to.
A few forums have had that problem, but it still mystifies me what the heck is wrong there. :/
I guess you could try just putting this block of code right at the start of the plugin on global_start:
PHP Code:
$questions = explode("\n", $vbulletin->options['nospam_questions']);
$nospamnumber = array_rand($questions);
$qanda = explode(":",$questions["$nospamnumber"]);
$nospamquestion = $qanda[0];