I have a T6534 eMachine with a K8NGM2 H motherboard. All 5 USB Ports have perferral power but no signal and therefore the USB hardware (like a keyboard, camcorder, ipod, etc) when plugged-in is not recognized. The Windows xp Device Manager indicates all systems are working properly. Uninstalling the USB controllers and Hubs and then letting Windows find them on boot up doesn't help. Disabling all USB from the AMI BIOS settings, rebooting, then Enabling and booting doesn't help.

A possible "work around" would be to purchase an expansion board with USB ports. Before doing that, I wonder if there is anything else I can do to re-establish the on board USB that had always worked before.

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If it worked before, was there something that changed at roughly the same time the USB ports stopped working?

Hi - Good question! However, it's been a couple of years and I frankly don't remember if there was something else I was doing that could have caused it. It seems that all USB ports didn't fail exactly at the same time. But if I made some change, it was certainly not a major one. I think the configuration of the computer hardware is the same as it's always been. So this is quite a mystery to me.

Sometimes (not always) this helps:
You could try to turn off the computer, take all cables off. Then unplug the power cord for 3 to 5 minutes. Then put everything back one by one.

Had this problem with a client's HP laptop. The built-in USB ports would work for a while, then magically disappear. No amount of work on them would work. Then they would magically work again for a while. Others also reported this problem though there seemed to be no answer from HP or Microsoft. I suspect it was an address conflict, but that is speculation.

The workaround, in this case, was to buy a PCMCIA card with 2 USB ports. Not pretty, but it worked consistently for the remainder of the life of that laptop.

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