global_bootstrap_init_start code causing 301 redirects

[sacobra]

I have got this the following code in global_bootstrap_init_start hook for Janrain plugin.

$engage_token = $vbulletin->input->clean_gpc('p', 'token', TYPE_STR); 
$engage_callback = $vbulletin->input->clean_gpc('g', 'engage_callback', TYPE_INT); 
$add_engage_identifier = $vbulletin->input->clean_gpc('g', 'add_engage_identifier', TYPE_INT);

However this code is causing a 301 redirect when accessing the home page (content.php).

When accessing the URL http://<domain-name>/ it is redirecting to http://<domain-name>/?engage_callback=0&add_engage_identifier=0

Would anyone know how to fix this?Regards