If you repeatedly get errors while installing your new scanner, printer, or other devices, you might need to delete the drivers of the old device from Device Manager, and start the process all over again. Windows only shows active devices in the device manager, and to remove the drivers of the old printer or scanner, you must connect the device again to the PC. If this is not possible, the invisible devices will stay hidden. To delete the drivers, press [Pause|Break] when holding down the [Windows] button. This will throw up the System Properties window. Click “Advanced” in the window and then on “Environment variables”. Now click “New”. In the next Window, type “devmgr_show_nonpresent_Device” next to “Variable name” and type the number “1” in the field next to “Variable value”. Close the window, click the OK button on the System Properties window and restart the computer. Once the computer restarts, press [Pause|Break] when holding the [Windows] button again. In the next Window, click “Hardware” and then on “Device manager”. In the following window, go to “View” and activate “Show hidden devices”. Now the devices that are not connected will appear, but the rogue drivers are still installed. Right-click on the concerned device in the Device Manager and uninstall it along with its drivers.