2 computers in same workgroup -Vista and Win 2000 - Can't logon

I cannot logon to a Win 2000 machine from a Vista Machine or Vice Versa (all
I want to do is check that the files copied over OK from one machine to the
other - its not as simple as using Microsoft's tool to do this as I want to
delete old files and tidy up the directories - so the files are not in
exactly the same place on the new machine as on the old machine- I actually
ended up copying them to an external drive on another XP machine which I then
moved to the Vista Machine if you want to know how the files got across in
the first place).

1. I have Vista Ultimate on new machine - HEYVIIV
2. I have Win 2000 on old machine - HEYDELL
They are both in the same workgroup HEYMASH. On both machines I can see the
other machine in the workgroup using Network, My Network Places respectively.
A Linksys Router (Etherfast/DSL Router) gives out DHCP IP addresses to both
machines. I have Norton Internet Security and set the MAC number of HEYDELL
to be a trusted machine on HEYVIIV, also the network MAC number (i.e. the
MAC number of the Linksys Router) is Trusted and the network is set to
Private. I have not turned the Norton Firewall completely off. File Sharing
is On according to Vista, but its grayed out and I cannot change it in the
Network and Sharing Center, where Turn On File Sharing is checked and it says
You Can Use Your Firewall Program To Change This Setting (I assume this means
that file sharing is on).

3. On the network there is another machine running XP, YMASH. There is an
error in the Event Log that says Event ID 8003.
The master browser has received a server announcement from the computer
YMASH that believes that it is the master browser for the domain on transport
NetBT_Tcpip_{2DFB2E87-E0B0-4529-8BB9-175113EA0076. The master browser is
stopping or an election is being forced. - I don't think this is a problem
for connecting HEYVIIV and HEYDELL but I put it here for completeness (how
does one know which browser is in charge...).



A. HEYVIIV LOGIN PROBLEM TO HEYDELL
When I am on HEYVIIV (Vista) trying to logon to HEYDELL (Windows 2000)
The login screen comes up. I type a login name, say Administrator. On XP
client machine I type the password and am logged in. On Vista client
(HEYVIIV) when I type the password the name gets changed to
HEYVIIV\Administrator. So I try a new login name HEYDELL\Administrator - the
window disappears and then comes back and is not logged on (in XP it would
logon OK with the login Administrator - but I can't use plain Administator as
the Vista Machine keeps correcting my typing.) What should I do???

B. HEYDELL LOGIN PROBLEM TO HEYVIIV
When I go to the Win 2000 machine, HEYDELL, and try to login into HEYVIIV
there are two cases:
a) Password Protected Sharing is ON
In this case no login window appears and although I can see the folders that
I've set to share by setting their properties it says Access Denied. Even
folders dragged into the Public folder can't be seen because when I click on
Public I also get an Access Denied message.
b) Password Protected Sharing is OFF
Same problem - I can see the folders and the only one I can get inside is
USERS and then each folder in that is shown as empty.
HOW DO I GET A LOGIN SCREEN TO COME UP ON HEYDELL (Win2000)?

I can't believe it is so difficult to essentially mount drives across a home
network!