with the scanner disconnected, uninstall the scanner, if it's in programs and features and also remove it if it's still in start, control panel, scanners and cameras. If it was there, then restart your computer.
Go to device manager(right click my computer, left click properties, left click hardware, left click device manager)
Go to the USB Controller section and click the + sign.
Starting at the bottom, USB Root Hubs, and working your way to the top, USB Universal Controllers, un-install everything in that section.
Restart your computer. Windows will find everything again and correct the problem one.
Reinstall the printer / scanner