TCP/IP Problem (Urgent)

I have a Class C Network 192.168.1.0, the subnet mask is 255.255.255.0, there are 20 nodes on the network.

Problem :- All my nodes are able to ping 192.168.0.1, but they are unable to ping each other, I have tried re-installing the Network drivers, but I am still unable to make the network work.

Please Help