If your multihomed Windows 2000 computer leaves a domain, after applying Service Pack 1, you might not be able to rejoin the domain.
The problem has been fixed in Service Pack 2 (and later), but until they are available, try any of the following workarounds:
1. Disable the onboard NIC.
2. Unbind Client for Microsoft Networks from the onboard NIC.
3. If you are able, uninstall SP1.