Network browsing takes ages when one computer is declared ..

Archived from groups: comp.security.firewalls (More info?)

I've a small network made of 3 computers plus an additional one, the guest,
connected time to time (IP address 192.168.0.100).
I configured ZA to consider this address as belonging to an Internet Zone.
The other PCs have of course a fixed address, resp. 192.168.0.10,
192.168.0.20, 192.168.0.40.

The Internet connection sharing works well from everywhere (an USB ADSL
modem is connected to a gateway running Win98SE).

But the windows file explorer doesn't recognize any network when this
guest's PC is connected.
In the same time I can copy files from one computer to another one with
batch files, giving the full link :
copy \\computer_1\source_dir\source_file.ext"
"E:\target_dir\target_file.ext".

Somebody can explain ?
Thanks