like a sound .wav selected for a particular action in Sounds & Audio devices in Control Panel.
Open that, click the Sound tab, scroll down and test each one with the play button in the dialogue window, and see if you get the same clicking sound. If so, likely that's your culprit, and it is being magnified when you play WMP.
I've got Windows 2000 at the office with the IE browser. When I am listening to music through the radio tuner offered in Windows Media Player, I get a loud click in the music each time I click the mouse to go to another website or newspaper article. That seems like such a simple 'overlook' on the design end, and I'm wondering if there's anything I can do at my end to stop having that occur? Thanks much. Eric