Win2000 Server and Win98 OS

I have both of these computers networked to each other. However, at various times, Win98 seems to drop from the network. I’ve tried unhooking the cable modem,turning off Win98, turning off Win200 Server, checking the hardware for connectivity and nothing seems wrong. Then all of a sudden, one day Win98 shows connected to the server! Do you have any other ideas?
Thanks!