First make sure that you are using the correct CD with drivers supplied with your mp3 player or if you are asked to indicate the path to your driver, the path is correct.
Make sure when you install the drivers the mp3 player is connected to your computer and it is turned on. If you still get the error try to change the USB port(maybe the one you are using is damaged) and unplug all other devices from USB, except the mp3 player. You should also try to update your system with the latest Service Pack and hotfixes.

If the problem persists try to find another CD with drivers(maybe the one you are using is damaged) or download the drivers from the manufacturer's website.

If none of this worked try to contact the company which produced the mp3 player or your vendor to help you about this problem.