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does it show up in the Device Manager as Kinect for Windows? If not, it might show up as Primesense in which case try updating the drivers by right clicking on each part select Update Driver Software then Browse my computer for driver software the Let me pick from a list... If that doesn't work, I'm not sure what else to try as I'm a bit out of my depth. I don't know what software you're trying to use it with but to test if that is at fault, try http://reconstructme.net/ and see if it works with that.
This worked for me! I was having issues at first, it failed to connect in reconstructme, but it turned out I had an early SDK/drivers installed. After installing Kinect for Windows V1.8 from here: http://www.microsoft.com/en-us/download/details.aspx?id=40278 it works!
Have you installed the Kinect for Windows SDK v1.8? get it from here: http://www.microsoft.com/en-us/download/details.aspx?id=40278