The trigger for this error is:
#load config info
if(file_exists(ROOT_DIR.'ostconfig.php')) //Old installs prior to v 1.6 RC5
require('ostconfig.php');
elseif(file_exists(INCLUDE_DIR.'settings.php')) //New config file.. v 1.6 RC5 +
require(INCLUDE_DIR.'settings.php');
else
die('<b>Error loading settings. Contact admin.</b>');
So I would guess that your settings.php file is missing.