I have several Vista Pro workstations on a domain with a DC running Server 2008. When I view the Network and Sharing Center on the workstations, Network Discovery shows "Custom" with a green dot. If I try to switch it to "On", it will not switch. On the DC, I set the following in both the DC GPO and workstation GPO: Computer Configuration -->> Administrative Templates -->> Network -->> Link-Layer Topology Discovery -->> Turn on Mapper I/O (LLTDIO) driver Computer Configuration -->> Administrative Templates -->> Network -->> Link-Layer Topology Discovery -->> Turn on Responder (RSPNDR) driver All rules related File and Printer Sharing and Network Discovery are allowed in the DC firewall. Is there something else I can try at this point? This may be related: The workstations can connect to the server's shares and navigate through them (there are several). But when I attempt to copy a file to one of the local workstations, the copy starts but does not complete and I get a message:"Windows cannot access \\Server\ShareError code: 0x80070035The network path was not found."At that point, I lose network connectivity and have to restart to get it back. Any help is appreciated.

I reinstalled the OS on the Vista clients. That resolved the issue.