No volume playing .wav files

I have a user that can play audio cds with no problems, but can’t play .wav files. I should say she can’t HEAR the .wav file when it is playing. The system is W2K SP1 and the .wav is being played by Windows Media Player 7.01.
I’ve checked every volume control that I can find and all of them have .wav slide bar maxed. I have run out of ideas. Has anyone else had this problem?
I send voicemails to my users as .wav files so that they can listen to them over the computer speakers. All the other systems, both NT 4.0 and W2K, have no problems, just this one! Thanks in advance.

Roger