Windows 2000 detects the "link state" of a network adapter, using the same technique that a hub uses to enable a "link" light. This ability is called "Media Sensing".
NOTE: Windows 2000 does not attempt to detect "link state" if 10b2 or coaxial ethernet cabling is used.
NOTE: "Media Sensing" provides the roaming user the ability to connect to any network without having to restart, release, renew, etc..
NOTE: "Media Sensing" allows a PC with two NICs to unbind all traffic from a 'failed' NIC and to move it to the other NIC, if a default gateway is present.
You can disable "Media Sensing" using Regedt32 to navigate to:
On the Edit menu, Add Value name DisableDHCPMediaSense, as a REG_DWORD data type. Setting the data value to 1 causes DHCP clients to ignore "Media Sense" events.
You must restart your computer for this change to take effect.