I recently changed a Windows 2000 Small Business Server from being a multi homed machine where one network card was used to connect to the internet via an ADSL modem using a static ip address. The other card was using a private ip address for the local lan. I changed it because I had installed a hardware firewall and didn't need the 2nd network card any more. I then got the "The Directory Service Referral interface failed to service a client request. RFRI is returning the error code:[0x3f0]". After searching experts-exchange I then tried going into the network settings and then into advanced and making sure that the LAN was at the top and that file and print sharing was enabled on both cards. This appeared to fix the problem. However on rebooting the server reported that there was a duplicate name on the network and people were not able to access their email on the exchange server. I was also not able to browse to the sysvol share on the server from the server. By enabling and disabling the file and print sharing again and changing the binding order again and then back again I am able to make it work but often on rebooting the error will re-occur. I have had to leave it with both network cards installed and the second network card still configured as a private ip address to make this work in the short term. I have tried removing one network card and then trying the other network card on its own but am unable to get it to work at all in this configuration. Every time Microsoft releases an update that requires a reboot it trashes things again.