The LLTD Mapper in Microsoft Windows Vista does not properly gather responses to EMIT packets, which allows remote attackers to cause a denial of service (mapping failure) by omitting an ACK response, which triggers an XML syntax error.
http://www.symantec.com/avcenter/reference/Vista_Network_Attack_Surface_RTM.pdf
http://www.securityfocus.com/bid/23271
http://www.securityfocus.com/archive/1/464617/100/0/threaded
http://www.securityfocus.com/archive/1/462793/100/0/threaded