I have about 120 DELL Optiplex 390 running Windows 7.
All station have XP Mode installed (due to application not supported on Win 7).
Network Device - Realtek PCIe GBE Family Controller (On Board).
I tried using Shared Networking (NAT).
In both cases XP Mode keeps disconnecting for a few seconds up to 5 minutes.
Using Outlook I get a message saying connection to Exchange server Unavailable / Resored.
Ping to Exchange Server returns "Request timed out".
Checking network status on Win 7 shows there is no problem
Ping to Exchange Server reply OK