W2K Network Passwords

I am new to W2K Pro and have set up a LAN with 3 workstations on W2K Pro, 2 on Me and 1 on 98SE. The W2K stations can access all other workstations with no problems. The Me and 98 stations cannot access the W2K stations without a network password. I have not set any network passwords on any of the workstations. Does anyone know why the Me and 98 stations require a network password to access the W2k stations if none was set to begin with?