Balix,
Could you go to command prompt again and type ipconfig /all and report the output?
From this it will be possible to see the IP configuration, including whether it is DHCP or fixed IP address, what the subnet mask and default gateway are and whether or not DNS server entries are being passed to the client.
In a previous post, you say that manually entering an IP address interferes with your son's PC - this sounds as if you are assigning exactly the same IP address, which will conflict and stop the other from working.
Each PC (node in IP terms) must have a unique IP address on its local subnet. The subnet is defined by the subnet mask, which divides the 4 octets of the IP address into Network address portion and Node address portion.
Thus 192.168.0.1 with a subnet mask of 255.255.255.0 has a network address portion of 192.168.0 and a Node address portion of 1.
Therefore another node on the same Network must have a different Node address - thus 192.168.0.2, with subnet mask of again 255.255.255.0.
To talk to any other node, IP uses a simple compare operation (actually a logical AND operation on the binary digits of the IP address and subnet mask) to see if the destination is on the same network - e.g. is 192.168.0.1 on the same network as me (192.168.0.2)? In this case, the network portions are the same (192.168.0), so the answer is yes and the datagram is sent directly to the destination node.
If the destination address is NOT on the same network (e.g. 213.161.73.143, or 192.168.1.1), then the transmitting node sends the datagram to the Default Gateway to be forwarded to the correct network.
Thus endeth the lesson
