If you have Windows xp then the drive is most likely faulty.
You may need a driver for it but not normally for xp. If it has worked in the past it that same USB port then its faulty. Try it in a different USB port, there may not be a enough power to the drive.
the link takes you to the web site for Integral
http://www.integralmemory.com/tech.aspx
andytheit
September 2007