Cannot acquire network address

My home is setup with a router connected to DSL. One of my PCs was working great, and then now it cannot acquire a network IP address from the router. I checked every possible setting, and even used my laptop on the same cables and router, and the laptop connects no problem, but my PC shows the IP address of 0.0.0.0 and when I try to repair it, it says Cannot Acquire Network Address. And then it sits there for hours trying to get the address. The NIC is working properly, and I even tried a different NIC and got the same thing, it shows speed of 100Mbps and Status: Acquiring network address. I tried uninstall and reinstall of the NIC………… anybody got anything?