If a host NIC is added after Avanti has been installed, it will not show up on the configuration utility pull down list.  This is because the Avanti PCAP driver does not see the new NIC.  To make the NIC visible to PCAP, open a cmd window, run “net stop msipcap” followed by “net start msipcap” to restart the Avanti PCAP driver.  Re-installing Avanti and rebooting Windows will also correct the problem.