I had the same problem, I fixed it with different drivers. When I get home I will check to see what it is exactly. I have this problem because I have 64-bit Vista and more than 2GB of memory. This is known issue, and Creative is supposedly working to correct it. Here is the link to their beta drivers. Its only for systems with 2GB or less at the moment.
Edit: I remembered the name of the drivers, YouPax. Search around and you should find what you need. If not I can give you the filename of the driver files.