Win98SE system can't ping / be pinged / explored but shows up in Neighborhood

I am adding a WIN98SE system to a LAN.
The workgroup name is consistent.
The IP addressing is consistent.
I have followed Carey Holzman's rules for configuration after somewhat
simpler settings failed.


This computer sees nothing in the workgroup (it appears) but sees itself on
the network.
It can ping itself and localhost 127.0.0.1

The other computers find the Name of this added computer in the Workgroup.
However, they can't see inside it - as if it's not there.
Same result on different LANs.
Yes, file sharing and a folder are shared.

Pinging doesn't work.
DHCP doesn't work.
APIPA assigns IP addresses OK.
The routing table looks normal.

I have tried various cables and switches.
I have installed a different NIC.
I have reinstalled drivers multiple times.
I have reinstalled TCP/IP at least a couple of times.
I have tried it on 3 separate LANs - usually simply with another computer
(XP, ME) - also on a bigger LAN.

Same results.

Any suggestions? It almost seems like there's a layer missing. The system
was upgraded from WIN98 to WIN98SE before all this started.

Thanks,

Fredd