PCM2707 don't sing with window 7

So I built a little USB DAC with PCM2707 with WM8727. It was singing nicely when connected to a Macbook Air. When I tried it with Asus running Window 7, the computer recognises the device and loaded the driver automaticly. But after 30 seconds the dac disappeared from the list of output devices. I cannot find it anymore after reboots or replugs. But there were no warning messages like usb device fail. So it doesn't look like a driver issue and the computer simply ignores the presence of the device. Tried the dac on an ancient Compaq with XP, it worked. Any ideas why.