Brian - it would be the whole network cabling food chain. Ie., look at the cables to switch. Make sure there are no switches daisy chained. Make sure there at least 100Mbs swtiches, etc. We also had an issue that was caused by an auto negotiate between the workstation and the server. We had to force the switch to 100mb as the NIC in the workstation would not support 1GB, but the switch would not step down by default.