I also own a Santa Cruz sound card. Awhile back Turtle Beach posted MICROSOFT CERTIFIED drivers. I installed them. They installed fine and the old drivers were removed. I tried later to uninstall the drivers from the add & remove programs and the driver uninstall program could not find the uninstall file for the Santa Cruz drivers.
I ended up doing a format C: and a clean install to recover. Turtle Beach may be able to tell you what files to delete to save you from having to take such a drastic measure.