Nutter helps a reader battling a bad hub/switch or an electrical problem
I have five machines that when booted, hang at the Windows splash screen. They are a mixture of Windows 2000 and XP Pro clients. When I take these same machines to my office, they boot up fine and connect to the network. But when I take them back to the customer network, they start having connectivity problems. After several days of bringing in brand-new systems, reformatting, OS repairs, cable changing, etc., I discovered that if I unplugged the Ethernet cable from the back, booted to the logon screen, plugged the cable in and logged on, everything was fine. Obviously this is not the way to go. Do you have any ideas? No one I have talked to has ever seen such a thing. I’ve replaced the cables from the machines to the patch panel and switches, and these machines have nothing in common as far as location on the switches or patch panel.
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What you’re describing sounds like either a bad hub/switch or an electrical problem based on what you have tested so far. I would take one PC from your office to the customer location and see if it acts up like the ones at the customer location. I would expect it to based on what you have seen so far; I’m trying to see if the problem shows up on a machine that has never been on the customer network. If your machine shows the same symptoms, try a different hub/switch at the customer location. Put the test hub/switch in the same location as what is currently being used. Plug the workstation connection into it and into the network. If the problem goes away, but you can’t login, move at least one of the servers over to the test hub/switch and repeat the process. If you have partial success or still can’t login, you may be fighting more than one problem. If the problem goes away, you’ve isolated it to a bad hub/switch.
The next problem you might have will be harder to trace. You have one or more bad grounds. Testing for this will be easier if you have a digital oscilloscope or know an electrical engineer who knows how to use one. Using an oscilloscope will make finding a bad ground or working problem a little quicker to find. Don’t depend on the quickie $20 testers you find in a hardware or electronics store. You might have some success with an APC-brand surge protection strip. Every time I’ve found a problem with the digital scope, the APC surge strip has also shown a problem. Also make sure that the outlets are wired correctly. See if all the problem workstations are being fed by the same power panel (i.e., breaker box to most of us). If your network is being fed by different breaker panels, you may be fighting a ground potential difference. This will definitely take an electrical engineer to figure out. One possible resolution will be to use fiber optics to feed the portions of the network that are fed by different electrical panels to electrically isolate them from the case of the problem. This may not be a cheap fix but one I’ve had to use on more than one occasion to fix a similar problem.
