Or switch off EAX support and/or upgrade or downgrade (!) your EAX driver?

Creative drivers are a bitch for sure but you could try uninstalling and reinstalling them. I don't recommend "manual uninstallation" - weeding out registry entries and files by hand - but that's also an option. (My Windows XP was installed 5 years ago and I managed to fix all weird behavior so far.)

I know how you can get your card to be seen again, uninstall the realtek drivers, restart PC with your x-fi card in and install creative drivers.