Laptop not accessable

I have two pc's both on XP Pro and two laptops, one on XP Pro one on Vista.
They are all on a home network with wired pc connections to my router and the
laptops are both wireless to the router. All the machines see the Internet
and all but the XP Pro laptop see each other on my home network. Windows and
Norton firewalls were turned off on the laptop and the network reconfigured
to no avail. The PC can ping the problem laptop and the problem laptop can
ping the pc. However the pc shows the laptop on the network but when clicked
it is not accessable. The laptop only shows itself on the network despite
reconfiguring. What would be my next step to get the problem laptop on my
home network?
TX - Jim.