I had problems removing wmp11 and after hours I found a solution and now FairUse4WM is working perfectly. To remove wmp11 try the following thread:
How to uninstall Windows Media Player 11 in Windows XP

ALSO Make sure you have individualization your system. Visit the following URL to automatically individualize your system (use Internet Explorer only):
services.wmdrm.windowsmedia.com/indivSite/en/indivit.asp