Instructions:
My Computer——Properties——Hardware——Device Manager——Universal Serial Bus controller——Right click the Unknown USB Device——Update Driver——Install the software automatically.

How do you Update USB driver on your PC Automatically?
No matter what kind of software you use, generally there are only two steps. First, scan the PC with one click. Second, update the outdated or missing drivers in the scan list to fix the driver problems.

1. Fix USB printer and modem problems:
The symptoms of malfunctioning or incorrectly configured firmware might be unusual. Typically, when you remove and then re-add a USB device, the device simply becomes available again. However, the device may appear as a second instance of that device, and load itself as such in Device Manager. If you see duplicates of a device, verify that you have the most up-to-date firmware for that device. A similar issue that has the same cause occurs when a device loads a device driver and then adds a second device for which there appears to be no driver. The second device is displayed with an exclamation point in a yellow circle in Device Manager. The device may work correctly, but you cannot remove the "ghost" device until you unplug the parent device that seems to have generated the ghost device. You may be able to resolve this issue by updating the firmware or the driver for that device.

2. Fix Unknown USB device:
A: XP system keeps showing unknown USB device pops-up even you did not plug in any USB device. It is possible that there are conflicts among hardware or the motherboard driver is not working right. Reinstalling the motherboard driver can fix the problem most of the time.

B: You system can not recognize the USB device when you have plug it properly. Reinstalling the driver using the Device Manager as above when you have found that the driver is missing.