What is the make/model of your computer?
If you go to properties of that unknown device, any indication on what it is?
You can go here, search by product, make sure everything is up to date on firmware version. http://www.acer.com/ac/en/US/content/drivers
What all usb devices are plugged in?
See if you can unplug 1 at a time to see if this unknown device disappears in device manager to determine what it is.
Go here scroll to bottom, is this something you have? Go to the corresponding hardware you have and they have drivers listed.
Checking in to see if you still need help with this issue, if so please reply at your convenience.