If no one has tinkered with the settings it looks like the ethernet cable is bad.
I've moved an older computer from the basement where I used a Lynksys Wireless G USB Network Adapter for internet access to an upstairs office. I now want to connect directly from my Lynksys Wireless G Router to the PC to boost the speed (it's not a high-speed USB port), but when I make the connection, the browsers don't find an internet connection. I have the same lack of success by connecting directly to the cable modem and bypassing the wireless router. How do I tell the PC that I'm no longer using the USB connection and want to use the ethernet connection? I'm running XP on a Sony Vaio.