This may be old hat to some, but I am at wit's end. In brief, I can't get two peer-to-peer networked Win98 computers to see each other all the time.
Details:

Computer #1 is Win98
Computer #2 is Win98SE
Each computer has its own dynamically assigned IP address from AT&T, no IP sharing.
LAN setup is this: AT&T cable -> Surfboard Cable Modem -> LinkSys 10/100 Switched Hub -> 2-computer LAN.

Everything was working fine with both internet connection and local file sharing handled by TCP/IP. Then the AT&T server switched the WinSE computer's IP address to a different gateway and subnet. As a result, both machines still had good Internet access, but lost local TCP/IP connectivity.

To restore file sharing I installed NetBEUI on each machine and made it the default protocol. Now the Win98 box can see and access the 98SE box in Network Neighborhood (sometimes) but the 98SE box only sees itself (sometimes), so file access on the LAN is one-way only at best. I was able to send messages both ways using WINPOPUP.EXE, so the machines are connected in spite of what Network Neighborhood says.

AT&T is no help and this is making me crazy. If you're wondering why I used two IP's instead of a router, the LAN is primarily for gaming and I didn't want address conflicts when both computers are tied into the same game server on the internet.

Detailed current network configuration for both computers is as follows:


Installed components
------------------------------
Clent for Microsoft Networks
Etherlink 10/100 NIC
Dial-Up Adaptor
NetBEUI -> Etherlink 10/100 NIC
TCP/IP -> Etherlink 10/100 NIC
TCP/IP -> Dial-up Adaptor
File and printer sharing for Microsoft Networks

Primary Network Logon: Windows Logon

File and Printer Sharing: file access enabled


Client for Microsoft Networks Properties
-----------------------------------------
Network logon options: Quick logon



NetBEUI->Etherlink NIC Properties
---------------------------------
Bindings:
'Client for MicroSoft Networks'
'File and printer sharing for Microsoft Networks'

NetBEUI is set as the default protocol


TCP/IP->Etherlink NIC Properties
--------------------------------
Bindings: none
IP Address: obtain IP address automatically
DNS: disabled
WINS Resolution: disabled


File and printer sharing Properties
-------------------------------------
Browse Master: automatic
LM Announce: no

Solved!!

The Win98 computer had not been updated to ServicePack1. That seems to have fixed it. I also set BrowseMaster to "enabled" on the Win98SE machine to speed up network recognition, but it wasn't strictly necessary.

Contrary to what I read in several places, it was NOT necessary to use Client for Microsoft Networks as the default login. Windows Logon works just fine, with no logon passwords.

Thanks again for the links.