If there are several open programs on your computer, this latter cannot open the USB drive connected to it whereas you need to copy data from it to your hard disk. Therefore, a tool like USB Grabber is always essential.
USB Grabber is a tool to automatically copy the contents of your USB key as soon as it is plugged to your computer. After installation, you only have to select the default destination folder of the copied files so that it starts detecting the presence of removable devices without your intervention. Finally, this software is free and only uses 1MB of your hard drive.