Win98SE cannot shutdown because of network connection

Win98SE machine on small network (two machines).

The win98 machine cannot shut down because it appears unable to disconnect
from the network.

e.g. Just downloaded updates from the Windows update site, the machine tries
to shutdown and restart but becomes stuck with black screen because it
cannot shut down.

How can I disconnect the machine from the network and allow proper shut
down?

Should I have to do this?

Roger R