Hi All,
Sorry if I'm reviving an old thhread, but this has been of use to me recently and there is some confusion that I hope I can clear.
What you need to do first is contact Cambridge via their tech support. You'll need the serial number from your DAC.
Let them know that you need a firmware upgrade for your DAC as the driver updates online are only compatible IF you have updated the DACMagic first.
With regards to the lovely "Norton". Ditch it. Norton and McAfee are the biggest, bloatiest resource consuming "virus" protectors out there. I hate them, both from a home user point of view and as an IT professional. The best one by far is ESET. There are no malware or trojans in the official cambridge releases, what Norton is describing is a "PUP" (Potentially Unwanted Program). Norton and McAfee treat everything as "danger danger!! System attack! you know nothing so we'll use up more system resources and take advantage of you not knowing what we're talking about!"
I'm currently waiting for Cambridge to assist (only been 30mins), in the mean time though I (as can others) can use 48k for what it's worth (remembering its either upscaled or downscaled).