NT4 Network Connectivity problem

I bought a new Dell server to replace my old home-made box and installed and updated NT4. I have a small network divided into 2 subnets. After entering all the user accounts and setting the shares and permissions on the server drives, i have a problem. Any user can log in and browse to the server and see the shared resources. They cannot connect to them, however, unless I drop Domain Users into Domain Admins group (an obviously horrid solution).

I’m open to ANY suggestions here, I am tearingmy hair out. I’ve tried unsharing the drives and using the Wizard to set permissions,with the same results.