whats wrong with my network ??!!

hi guys,

I have an NT server with 95,98 and 200 clients.
One of the 2000 machines can only see the other 2000 machines and the nt server (i didn’t get to check that the other 2000 machine were in the same predicament)
I have a machine on a workgroup by its self who can see about half the machines in the domain(2000 and 98) but can’t be seen by anyone, only pinged.
Does anyone have a clue about what the problem could be ?