most drives with write protection have a physical switch on them, check for one, if not then it's either windows being dumb as it often is or there is software on the drive preventing it from being written to, Is it a U3 drive (comes with security software or portable software usually) I would suggest trying it on another pc and if you get the same error then back up you data and low level format the drive (you may need additional software for windows but *nix operating systems can do it out of the box in most cases)
slyde
August 2007