We recently upgrade our network to W2K, and there is a NT4.0 with Proxy 2 that is on the same TCP/IP network. The Proxy 2 has only one network interface ? a NIC, and it is a downstream Proxy that is pointed to the upstream Proxy through a router. This box has Domain Filters configured, and it works fine on NT4.0 network. After the upgrade to W2K, I installed Proxy 2 Client and Adminpak.msi onto a W2K Pro box. I can access Internet, the Domain Filters are still working, and I can use Outlook to access POP3-based e-mail system from Internet, all the same as before (NT4.0 netowrk). But I have to spend almost 5 minutes to see the ?Active Directory Users and Computers? snap-in to pop up. If I uninstall the Proxy 2 Client, the snap-in can pop up in seconds, but I cannot access POP3-based e-mail system from Internet anymore. So, I think ISA should be the answer to W2K network. I tried to install an ISA on a W2K box with Integrated Mode (while keep the Proxy 2 box still up and running), and there is only one network interface ? a NIC, on the ISA box, the same as the Proxy 2 does, and configured it to route to the Upstream Proxy, the same as the Proxy 2 does. I keep receiving error message in Event Log on the ISA box, error code is 14120. According to Microsoft, I have to either install ISA in Cache Only mode, or install another NIC that directly connect to the Internet. This network is a part of corporate network, and does not have direct connection to the Internet, but through a router, and chained to Upstream Proxy Server(s). So, it does not seem that the 2nd NIC could work. (the 2nd NIC will still be on the same IP network as the 1st one.) I tried to reinstall the ISA in Cache Only mode, but Outlook cannot be used to access POP3-based e-mail system from Internet, and ?site and content rules? doesn?t work quite well either. We have to chain the ISA box to the Upstream Proxy, we need firewall stuff, and especially Site and Content rules to work; we also need access to POP3-based e-mail system from Internet. Basically, we currently just need what the Proxy 2 did on the old NT4.0 network. How can we achieve those? Please help. Mark Zhang