sometimes fixing creative problems can be a pain in the a*s.
My audigy2zs would keep resetting to 2.1 config on every reboot (i have 7.1 speakers), it finally took a reformat of the harddrive to straighten out the stupid thing, no matter how many times i uninstalled/reinstall (using creatives or 3rd party driver wiping tools), nothing would work.
I would dry uninstalling the drivers first (in safe mode preferably) then rebooting and reinstalling from the cd, then update with the newest drivers online.
or perhaps try driver updates first, although i'll assume you already tried that.
also reinstall directx if you can. i'm sure you've heard the drill before, drivers, drivers, drivers... i got tired of hearing it myself.
although i will say i reinstalled once before that and it didn't help, perhaps because the last time i also updated my bios (was 3 updates behind)...who knows.
good luck.