If you’re using any version of Windows, one of the biggest problems, even today is the slow speed of copying files. I experience this just a few days back when trying to clean up my external hard disk on Windows 8.1.
Anybody who uses a USB drive be it a pen drive or a hard disk knows how painful it can be when you run into the stupid “USB drive is in use” error everytime you try to eject the same. In such a situation, I normally rely on Unlocker to do the needful. However, that isn’t always solve the problem at one go.