We have a .Net 4 application that we are trying to migrate from W2k3 R2 to W2k8 R2 (both Enterprise). It receives data via PGM (Reliable Multicast). When we try to run the application on W2k8 R2 Enterprise we do not receive any data. The application does not receive any errors. When we perform a netmon trace, none of the PGM protocol information is captured. The behavior is as if the PGM session was never initiated, when in fact it has been. Reliable Multicast is installed on the network adapaters. The publisher is also a .net4 app and we were able to migrate it over to W2k8R2 without a problem. Both machines are on the same subnet The servers are multi-homed and the NICs are Broadcom Netxtreme II with TOE.