You need to understand a few things here. First, what protocol do you have installed, TCP/IP, IPX, or something else?
When a Windows 2000 client tries to access a remote drive, it will try to connect to it using NTLMv2, which is the security provider in a Windows 2000 environment. If you have a KDC (Key Distrabution Center Server), it will try using Kerberos first. If the client cannot connect using NTLMv2, then it will use NTLMv1 (compatibility for Windows 9x and NT 4.0 and 3.5x machines). The reason for this is if you are trying to connect to a Windows 9x or NT machine (a non-Windows 2000 machine), it will try to connect by sending the current username and password. This will not work if you are connecting to a Windows 9x box, but it will work quicker if you are trying to access an NT machine.
What type of client are you trying to connect to?