Cannot connect to share on new Win8 PC

The customer has an antique Win2000 PC, set up as a workgroup computer (not a domain), with a D partition shared as \\server\d.  There is an XP PC in the office, and I think a Vista PC, both of which connect to the share just fine.  

But today they went out and bought a new Win8 PC, and I can't get it to connect to the share.  One way I've tried is using "Net Use S: \\server\d".  Like normal, it asks for the user name and password.  After I key them in, it pauses for a few seconds as though it really is trying to connect, but always fails with an error 86, saying I have a bad password.

I know the login and password are legit, because that's the one that other PCs are using.  But I finally found a place to add users on the Win2000 PC, under contol panel> computer management> system tools> local users and groups> users, so I add a new user and password but that didn't help.  I also added a user that matches the name of his new Win8 PC, along with his new password, but no luck with that either.

In addition to the net use command, I tried to connect by browsing in Windows Explorer, getting the same response about bad password.  Windows Explorer 'sees' the Win2000 PC, but just won't connect.  I can also ping the Win2000 PC just fine.  I noticed that the screen where I key in the username and password says something about "Domain: JoeSmith" on the screen, which seems a bit strange to me since there is no domain involved in any of this.

So could all this be a compatibility issue betweeen the new Win8 and the old Win2000?  Any idea how to solve the problem and get connected?  TIA