« MODx Parse Error »

MODx encountered the following error while attempting to parse the requested resource:
« PHP Parse Error »
 
PHP error debug
  Error: shell_exec() [function.shell-exec]: Unable to execute 'host -W 1 38.107.179.221' 
  Error type/ Nr.: Warning - 2 
  File: /var/www/modx-0.9.2.1/assets/plugins/slimstat/_functions.php 
  Line: 456 
  Line 456 source: $host = shell_exec( "host -W 1 ".$_ip );  
 
Parser timing
  MySQL: 0.0184 s s(19 Requests)
  PHP: 0.1152 s s 
  Total: 0.1337 s s