According to this post at ravenphpscripts.com, the problem is with the site's IP2Country tables.

http://ravenphpscripts.com/postt7780.html

In that post, Raven suggests commenting out the code that checks for invalid IP:

• simply edit includes/nukesentinel.php. On or about line 140 find
  
  

  Code:

  // Invalid ip check if($nsnst_const['remote_ip']=="none") { die(_AB_INVALIDIP); }

  and comment it out

Otherwise, the IP2Country tables need fixing.