I am pulling my hair out at this point. I can't for the life of me figure out why this is happening... We have a couple of computers that keep telling me that the ethernet cable is unplugged or is broken. I've replaced the cable both going from the wall to the computer and also from the patch panel to the switch, to no avail. I've used a toner and probe and I can read the tone perfectly without a problem. It is patched to the correct patch panel port and everything is good. I don't see lights on the NIC part of the laptop where the cable goes in, but I don't know if the laptop has lights, I don't think it does. On the switch, all the lights come on like they should. I also have tried using a different switch and it still doesn't work. Why do you think this keeps happening? I can't figure out what could be causing the NIC to be not responding when plugged in with a cable.