Disappearing Computer

I had set up my computer WIFI network on two Win98SE
machines, one computer connected through a wireless router
and the other connected by wire to the router. After
initial success, I set up some shortcuts from the wired
computer to the WIFI computer. Later, while
troubleshooting some efforts at beefed security (all
router based), I had to reinstall drivers etc., on the
WIFI machine. Now, the WIFI machine cannot see the wired
machine at all, but can be accessed through the shortcuts
on the wired machine, although it cannot be seen in
Network Neighborhood on the wired machine. Shortcuts on
the WIFI machine return a network not found error. Both
machines can share the router's internet connection.
What's up? What could be wrong? I am desperate.

TS