I have dell hardware with Server 2003 r.2 64bit, and also Exchange 2007 installed. This is acting as my complete exchange server. I have it connected to an HP 1800 Gb switch. The thing keeps losing network connectivity randomly and I can't find anything in the event logs. I have tried using the other NIC in the server and also change the ports on the switch. I don't konw if it is something in the Hub Transport that is causing this or not. Anyone have an idea or some place to start other troubleshooting?