Mapping Network Drive From Windows 7 to a Win2K Server

I cannot map a drive to a Win2k Server folder from Windows 7 Ultimate.
(The OS was previously Windows 7 Home Premium and was upgraded to Ultimate.)

The User Name and Password exists on the server and it is the same as the
one on the Windows 7 computer.

The User is a member of the group with rights to the shared folder.
(I have no problems with all the other systems that are running the gamut of
Windows versions)

Initially I couldn't even map to a Windows 2000 computer (not a server) but
was able to after
adding the user specifically to the folder's Sharing->Permissions and
Security
So I did the same on the Win2k Server, but it still didn't work.

When I try to map the error message says I may not have permission etc..

I tried to map the drive directly in the command pompt with Net Use.

In the Windows 7 computer I set:
Local Policies ->Security Options->Network Security: LAN Manager
Authentication level
set to: "Send LM & NTLM, use NTLMv2 session security is negotiated"

Still doesn't work.

Any help would be appreciated.
Let me know if I should post the question elsewhere also.

Thanks.