conflicting computer name.

hi my name is sameer. i work in a MNC co. as an network eng. i am facing a problem.the problem is this one of our user is getting a message duplicate computer name. only he is getting this error. i had check with all the the user, that they are getting this type of error they said on.
i had tried to change the name of the computer but no change th the situation. can u help me?