USB not recognized but "nothing plugged in": solved
I started getting a pop up balloon that a USB had malfunctioned or was not recognized. But there was nothing plugged in to the USB ports on the front of my PC.
Every time it happened the mouse would freeze so I could not click on the error balloon for more info. Then the mouse would unfreeze but the balloon was gone.
I did all the usual things suggested... driver checking, (all were supposedly working fine), rebooting, device manager inspecting, but nothing worked. FINALLY my mouse was close enough to the error balloon one time, and when I clicked on it, it said "the malfunctioning device will be highlighted". It was the darned mouse!!! (It wasn't highlighted, it was bolded.)
Anyway, I didn't think about the fact that the mouse was also a USB device because it was plugged into the back, outta sight....outta mind, and it worked other than freezing during the error.
So yesterday I bought a new mouse (wireless) and all is well. I feel mildly dumb about this one, but posted it because maybe this info will help someone else.