Network problem

[bobw]

My son has an all PC network at his office. He uses a Desktop on the Network, and has a Dell Laptop he uses also, to bring work to clients, and works at home with it. When he plugs the Laptop into the Network, it brings the entire Network down.

When he plugs the Laptop into his Router at home, he loses the Internet on his home Desktop.

Any ideas on what might be causing this?
Could a bad network card in the Laptop do this?

Thanks

[glc]

I suppose it could - and so could a misconfiguration. What version of Windows is on the laptop?

[bobw]

WindowsXP.

If it's a configuration problem, where to look?

This has work fine for almost a year.

[glc]

I'd remove all network connections and uninstall the network adapter in device manager, then restart and reinstall the adapter and local area connection.