I have four remote sites that each of them belong to a different subnets and
each of the remote sites has a router.  That this four routers are connected
by a frame relay. Previously I can browse the remote PC's on the other sites
thru network neighborhood.

But when I've installed a firewall on my network.  Specifically on the site
where I work. (The firewall is just behind the router from the frame relay.)  
I can't anymore browse the pc of the remote sites.  The only pc that I can
browse are the pc that belongs to my subnet...
I configured the firewall in a transparent mode that it just like acts like
a switch.  Also I disable the blocking capabilities of the firewall.  Also I
already enabled the WINS on my network, but still I can't browse the other
remote pc.

But I got a response from my "PING"

Please help me.

Thanks!!!