Connection to ISP and other users gone

Problem began days ago. I know a temp. Mech.Engineer was on the workstation(which was moved to a makeshift office temporarily) for about a week and he prob messed around because the computer was setup for the Head Engineer with Admin properties.

Problem 1: A WIN2000PRO Workstation has 'lost' its connection to the ISP(DSL Modem|Gateway) through our LAN. I have tried uninstalling and reinstalling TCP/IP and switching IPs. I have checked the DNS entries and they are correct.

Problem 2: Another weird thing, on the LAN it can 'see' several workstations in its Workgroup and several in another Workgroup but when you try to gain access to any of them it responds with an error of
"//comp_name is not accessible
The network path was not found."
The ONLY connection it can make is one to the WIN2000SERVER(Workgroup right now, no Domain setup or DHCP) in its workgroup which it makes after the user logs in.

To recap, I can ping the hell out of the W2K Server but can't get through to the gateway(DSL Modem 192.168.0.1) or any other IP address of a computer on the network.

Question: Could a Service/Policy control the communication only to the Server? Also since I can communicate with the Server then I can erradicate any possibility of it being a cabling issue. True?

I am pretty sure that both problems stem from one error.
I am new to Win2000Pro so ... ah don't be gentle just give it to me.
There is a fire lit under me by the Head Engineer to get it fixed. Please respond with any comment/help ... it is greatly appreciated.

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It is a damn poor day when you don't learn something.

 

If the guy was on your network with admin rights he can go to user manager and change any user account info he wants on your server....not a smart thing to have done but that's ancient history. It only sounds like he changed the workgroup name on the local PC or perhaps he has changed the computers name itself. Go to the server and look in server manager to see if it is part of your local domain or workgroup.

 

!!!SOLVED!!!I didn't think this was affecting it but I told the user to change it.

Under the configuration of the ethernet adapter there are settings for 802.1p Support(disabled on my comp), it was enabled on his computer. He disabled it to see what would happen. It asked to reboot ... in Win2000Pro when it asks you to reboot you know it is doing something important with the hardware! Well, it worked. PLEASE see " http://support.microsoft.com/directory/article.asp?ID=KB;EN-US;Q222020 " for further information. I do not understand why it worked yet but I soon will. Maybe you have to have it in all your hardware across the network or else it won't see that hardware. I do not know why the temp(problem causer) would enable it. Anyone have any ideas?

 

According to Microsoft:

Working at Layer 2 allows 802.1P to support IPX, SNA, AppleTalk, and so on