Some of the World Bank XML files currently in the registry include Unicode character 0x5, which isn't a valid XML character, and so many parsing tools will reject these files or fail to process them.

In PHP I've dealt with this with a simple search and replace running each file through the command: 

$data = preg_replace("#[\x5]#","",$data); 

There's some details about 0x5 and the XML Specification that helped me identify the issue here: http://osdir.com/ml/text.xml.exist/2004-10/msg00123.html