IP pinging

Hi come across a system has 2 NICs in it, one is for adsl the other is for the LAN. I can ping from this system out, but I can’t seem to ping back to this system from any other terminal on the network. This systems ip address is set at 192.168.0.2,as I said I can ping out and ping any terminal on the network, but when I try and ping it from any other terminal all I get is a timeout, Can any one help ?