If all else fails to resolve the issue you can always uninstall and reinstall the soundcard, that usually solved older Creative Soundcard noise issues.
yeah i have the newest driver and instaled it from strach but i had problems with windosez [viruses] and reinstaled it and installed the card again but same problem.
but i didnt try those Creative Diagnostics, i will now thx 4ryan6
i remembered before i went to bed that someone told me that lowering sound card acceleration in dxdiag can also help in some casses.
I have this same problem too, and it is the actual soundcard I believe....I have tried it on two different rigs, windows xp home and windows xp x64, and experience the same thing...I just live with it.