Cannot connect with ethernet cable, only wireless?

I have a Dell Latitude D630 that will not connect to the internet through a cable.  It connects fine using a wireless connection.  I tested the cable system on another laptop which was able to connect just fine so this is definetly a problem with my laptop not the cable system.  When I plug the cable into my laptop, a small red light and small flashing yellow light turn on just next to the cable plug in spot (when I plug the same cable into another computer that is able to connect, I see a green light and yellow flashing light).  I disabled my wireless network connection (under Control Panel, Network Connections) and also ran the "repair" function on my local area connection.  When I ran the repair function, a message popped up that said it could not repair the connection because it could not renew the IP address.  I have "Obtain an IP address automatically" selected under Internet Protocols (which worked fine on the other computer). I then tried to manually enter the IP address using the information from the working computer.  No luck.  I have had this problem before with this computer and someone solved it and I was able to connect using a cable for several weeks.  But since then I wiped the  laptop and I can't figure out how to do it again.  Thanks for any suggestions you may have.