Why is the network cable plugged in, yet unplugged?

Weird question, but I will explain. Basically, I just moved out of a residence hall to a new one. My ethernet connection worked perfectly fine there and the problem began once I moved into this new building. At first I thought it was the jack in my room, but I tried it in a new room and had the same issue. This is what happens:

I will plug the ethernet in while the computer is starting up and I will get the flashing LED signals on the port, but as soon as windows is started up (the start menu appears, etc) the signal is completely lost and the computer doesn’t recognize that the cable is plugged in. If I plug the cable in after the computer has started up, I won’t get a signal whatsoever.