Net Use Error 67 on Windows 2000

Trying to run a login script from a NT 4.0 server using a Windows 2000 client. Get a system error 67 on every net use command. Sample: net use G: \\server\G:
This same command works fine on a Win95 client. Everything I have read on Tech Republic says it should work. We need to resolve this before we can roll out W2K. Can you help?