usb ports on front of xenith stop working

usb ports on front of xenith stop working

Are there any known issues with the xeniths and the front USB ports? We have seen these occassionally stop working within a xendesktop session suddenly. If you unplug and replug it into another port in the front - it still does not work. If you take it out and plug it into one of the rear USB ports, it starts working again.

We have seen several Xenith's act in this same manner. anyone else?