The first thing i would try is boot in 'Safe Mode' and run 'Device Manager'. Then, uninstall ALL sound devices you find. Next, right-click 'Computer' from the start menu & select properties, then 'Advanced system settings' and under Hardware click 'Device Installation Settings' and make sure that 'Yes, do this automatically (recommended)' is selected. Next restart the machine. When Windows reboots it will start the 'New Hardware detected' wizard, and will check Windows Update to see if the drivers are available.
Once this is done you may/will need to install the latest drivers from the creative website in 'Cpmatability' mode for Vista/XP depending of the drivers you download.
Hope this helps