I have a Dell Dimension 6400 desktop running XP Home SP3 with 6 rear USB ports and two front USB ports.
A few months ago, I noticed a problem with my USB ports. When I plugged in a USB cable, all ports stopped working. If a device is already plugged in when I started the computer, there was no problem--only when I plugged one in while it was running.
So... I replaced the power supply because we noticed that the -5v was not working on the original one (the current one checks out) and completely wiped the computer using DoD standards, then reinstalled XP and all current updates, software, and my backup. Now there is a different problem.
When I plug in a cable after the computer is already running, it will not recognize that device, but the other ones seem to continue to work fine. It does not matter which port I use, it still happens.
I am running off of a very good UPS that has a one nanosecond clamp time, so I doubt if it was a transient of any kind. I am completely stumped. Any assistance would be greatly appreciated.
