How to Disconnect a Windows Computer from the Network
If you have tried all other network troubleshooting tools and methods, the final, and sometimes necessary, move you can make is to simply disconnect the PC from the network. You can do this physically, or you can break the connection by using software in Windows 7, Vista, and XP.
Here’s how to disable an Ethernet connection in Windows 7 and Windows Vista:
Open the Network and Sharing Center window.
Get to the window where you can view the status of your local area connection.
In Windows 7, on the right side of the window, choose the link Local Area Connection.
In Windows Vista, on the right side of the window, click the View Status link.
Click the Disable button in the connection’s Status dialog box.
Type the administrator’s password or click the Continue button.
Close the Network and Sharing Center window.
Follow these steps in Windows XP to disable the network connection:
Open the Control Panel’s Network Connections icon.
Double-click to open the icon representing the PC’s Ethernet connection.
Click the Disable button.
The disconnection is instant. In Windows 7 and Windows Vista, you see the red X marking the line between your PC and the network or Internet. In Windows XP, the connection icon appears dimmed with the text Disabled.
To reconnect to the network in Windows 7 and Windows Vista, click the red X icon between your computer and the Internet (or Network) icon in the Network and Sharing Center window. Obey the troubleshooter to enable the network adapter, which reconnects you to the network.
To reconnect in Windows XP, double-click to open the disabled-connection icon in the Network Connections window.