Cannot connect through router, only modem (strange problem)

[ppisciot]

I just purchased a new Asus P5N-EM HDMI motherboard. With a new installation of XP Pro and all updated drivers, if I connect from the LAN port to my cable modem, the lights on the LAN port light up and I connect with no problem. However, if I connect to my Belkin F5D7230-4 router, it says "A network cable is unplugged". I have two other computers that connect to the router and they all work fine. I have switched cables, had the Asus be the ONLY one plugged into the router and any other combination I can think of. I called Belkin and they walked me through several things including resetting the router. Again, works fine for all computers except the Asus. I even installed Vista; same result. Then I put an ide LAN card; same result! Any help would be greatly appreciated! Thank you.