Your network adapter should have its TCP/IP settings configured to get an IP address automatically. Check what IP address it is being assigned by the DHCP server on the network.
Open a Command Prompt window, type "ipconfig /all" (without the quotes) and press Enter. You should see details of the IP, DNS, Gateway, etc addresses, but the exact details vary depending on the version of Windows.
You should probably be getting an IP address in the range 192.168.0.xxx or 10.0.0.xxx
Set Internet Explorer's "Tools > Internet options > Connections" to "Never dial a connection", click the LAN Settings button and ensure none of the boxes is ticked.