UPDATE: The problem is corrected, after two years that even Dell couldn't correct! I thank all of you guys for your help because it was your many suggestions and advice that led me to the fault. I'm eternally grateful. I could leave it at that, but I know you are all curious, plus it may help someone in the future, so I'll relate the events. I went through many diagnostics, all that you guys recommended, and some I researched on the Net, but the problem persisted. I was almost at the point of a fresh install, but I didn't want to do that because I'm a professional writer and have hundreds of research files and couldn't be sure a data backup would get them all. After all of the last week of diagnostics, I rebuilt the USB driver stack, and finally went for broke and downloaded every (16) Windows update that I had hidden, the ones that Windows Secrets advised delaying. The USB ports failed again. (No surprise!) I uninstalled them. Last evening, I considered again what Scaisson had said about Logitech. Just after Dell furnished me with another OS on a USB stick in early 2013 and I loaded it, I also bought this Logitech k/b and mouse. When you plug the dongle (Unifying) into a USB port they all connect automatically. However, Logitech advises to go to their Net site and download their SetPoint utility which allows you advanced functions with the k/b, which I did. Last night I rebuilt the USB driver stack. The USB ports were working again. Then, because I'd tried everything else, and more or less just for the hell of it, I uninstalled the Logitech Setpoint, then I downloaded those 16 Windows updates again. The USB ports still worked! I've spent today trying many things to make the USB ports fail again, but they didn't. So, it was some fault with the Logitech Setpoint utility.
My hat's off you all of you guys. ;)
Glad you got it sorted. IMHO now would be a great time for a Full System Image. HTH :cheers: