Have You Checked the Cable
This was just a funny experience I had diagnosing a client’s network problem over the phone. Fortunately I had a young man on the other end of the line who reported accurately. (For those who receive customer service, one of the largest problems for the service tech is getting an accurate picture of where you are. If you don’t report precisely what light is lit, for example, you will make it much harder to resolve your problem.)
In any case, one network station was no longer able to access the server. We confirmed this behavior, confirmed that the problem was not with a particular shortcut, and then went quickly to checking little green lights on the network hub. The user reported absence of a light for that particular cable. Reseated cable, checked lights. Tried alternate jack, checked lights, nothing. Checked that cable was plugged into the back of the computer. (If you’re wondering why I had him do this after checking the hub, the hub is actually much more accessible in this case.)
That leaves network card and cable, neither of which is all that common a problem. He checked the cable. An animal had chewed it through. New cable and problem solved!
Oh, did I forget to mention this is at a veterinarian’s office?