Can’t access Win XP Pro

Network consists of one segment, Win2K Server, clients Win95/98, and one WinXP Pro. Can login from XP, and can access all other computers on network. From other computers, can see XP, but error message saying “device does not exist on network” whenattempting to access it. Can ping all other computers from XP, but cannot ping XP from any other. Communication appears to be one-way. What’s wrong?