Originally posted by: phisrow
It could also be that the cable in question isn't fully compliant with the USB spec, which might keep it from being certified(I'm not quite sure how picky MS is about that sort of thing). There are a bunch of fairly common, and useful, USB cables (male typeA-male typeA, Y cables, overlong cables, etc.) that don't actually conform with the USB spec. Cables longer than 15 feet would fall into this category, if I remember correctly.