Please have your XSL engine utilize a catalog and not dereference DTDs from us each time they are processed. For more on this issue and in the comments links to solution in different platforms see the following article:
http://www.w3.org/blog/systeam/2008/02/08/w3c_s_excessive_dtd_traffic -- Ted Guild <[email protected]> W3C Systems Team http://www.w3.org
