Network printer

In my office there have about twenty network PC.They are using Win 95, Win 98, Win 2000 and Win ME. Pcs using Win 95, Win 98 and Win 2000 can communicate and sharing file or printer among of them but I failed to sharing file or printer with pcs using Win 2000. Network password is requested although there is no network password at Win 2000 pcs.However Win 2000 pc os are not having a problem to communicate with another OS. Please help me…