I am seeing similar problems with multicasting using RapiDeploy (a similar product to Ghost). In WinPE 1.6 it works fine. In WinPE 2.x the peers in the multicast session see a few packets, but not all. The session ends up defaulting back to unicast and that works. I will look into the firewall disabling mentioned above since there's not much else to do at this point. One other test I thought of dealt with NIC drivers in WinPE. Does anyone know if the NIC drivers fir WinPE 2.x are compatible with the NIC drivers for WinPE 1.6? Could I drop a WinPE 1.6 driver into a WinPE 2.1 environment to see if the problem is in the WinPE 2.1 driver? If I find anything out, I'll post my findings in this thread.