This tweak is for all the people using a Soundblaster Live soundcard with Windows XP and the latest drivers from Creative. Somehow you are not able to run the program called Speakers located in the AudioHQ menu, but this will fix it.
1) locate the file called ctsurmix.exe in your creative soundblaster folder.
2) Right click it and select properties and then compatibility.
3) Select win2000 compatible mode and it should work again.