Try copying your MAC address from your working computer to the non working computer. Some ISP's allow you to build your home network with routers but it requires all the MAC address's to match. First you need to look up the MAC address on the computer connected to the internet. Here is a tutorial MAC Adress.
Once you know the MAC address of the connected computer you can copy it to the other computers on the net work. This Tutorial
Will tell you how to change it. Save the changes and reboot. Go back into IPCONFIG /ALL and check the address to make sure they match. This should resolve your problem.
Edited by Sneakycyber, 10 September 2007 - 12:19 PM.