http://blogs.technet.com/srd/archive/2008/06/10/ms08-036-pgm-what-is-pgm.aspxThis morning we released MS08-036 to fix two denial-of-service vulnerabilities in the Windows implementation of the Pragmatic General Multicast (PGM) protocol ( RFC 3208 ). You probably have never heard of PGM. Only one engineer on our team had ever hearden-USCommunityServer 2.1 SP1 (Build: 61025.2)