The Universal Serial Bus gives you a single, standardized, easy-to-use way to connect up to 127 devices to a computer. Unfortunately, the more you connect, the more possibility there is to have issues. If you’re using XP, then there shouldn’t be a problem but I try to limit USB devices to the fewest number I can. In addition, check the hard drive instructions. Some hard drives need to be connected directly to the USB port on the computer.