I am pressed for time on resolving this issue, so it is definitely worth 500 points to me to be able to get it resolved. I just completed a migration from Windows SBS 2003, TO Windows Server 2012 with Essentials installed. Out of approximately 40 Windows 7 Pro client workstations on the domain that are functioning perfectly well, I have five workstations that are constantly dropping off the network since the migration has been completed. The five workstations that are experiencing the dropouts, are coming off of a 3Com SuperStack 24 port managed switch, which is coming off of another of the same type managed switch coming off the new server. I had changed out the suspected switch, with an unmanaged switch this afternoon and still have the same issue. Within 15 to 30 minutes, dropouts began. Again, all other workstations on the domain or functioning correctly with no problems. Again this issue did not exist at all until installing and migrating onto the new server.