I just got a XMOS U208 USB to I2S Bus adaptor to try with a DAC. It loaded a bit differently than the other XMOS drivers. Before connecting the USB to the device, I started the driver load in Windows 7. It fully installed and finished. When I plugged the device in, it started by going to Windows update to look for the driver and took a very long time. The first XMOS driver then loaded and then started waiting again for the second. I selected do not go to windows update, and then it fully loaded the driver.
I would uninstall anything it loaded in Programs and reload the driver, then select not to use the Windows update version and see what happens.