Win98 access to win2k workgroup puter

I seem to run into this problem for some reason, two or three times a year. A win 98 computer attempting access to a Win 2k computer over a nat, w/ windows workgroup, the win 98 can not see the win 2k puter. I have set up user info, set permissions,and nothing works. The win 2k can search for and see the win 98, but nit the reverse. Please help.!!