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If you have a light out on a connected port, either there is 1) no power on the connected device, 2) the port on the connected device is defective or disabled or 3) the port on the switch is disabled. You can test to see if it is a switch port problem by moving the cable that is plugged in the working, lit port into the port that is not lit. If the port does not turn on, then the switch port is defective. If the light comes on, then the device that was previously connected to that port has a problem with it's network card. Can you do this test and then inform me of the results?
What happens if you move the cable from the port that is lit to the one is not?
So now all of the cables that are plugged in have lights now?
I see. So that is your Uplink cable for the second switch. Does the Credit Card machine have any issues?
It sounds like the PC that is plugged into the port is having the problem then. Can the PC connect to your applications or the internet?
It's possible that the NIC might be going out on it. You might be able to test it now and it will work fine but it might be starting to fail. What type of PC is this?
A faulty network card would cause application lock ups too.
Do you know what the model number is? It should be on a tag affixed to the side or back.
It looks like the NIC is on the motherboard but there are 2 PCI slots for adding a new NIC card. Do you have something like a Best Buy near you?
Well it doesn't look like Best Buy sells those cards anymore. Do you have another computer store near by?
They do sell them on Newegg and they are very reputable. I use them all the time. If you can wait a little while for it, it's very cheap and easy to install. Here's an example of what will work with your PC.
This one will work too. It's a little cheaper.
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