Losing USB on X31, reboot required

[GpsPasSion]

Been noticing this more and more, I regularly switch devices on the USB ports and it seems that they some not all stop getting recognized at some point, USB card reader OK, USB GPS not, etc.., no more "bong" when connecting, only fix is to reboot. Anyone else noticed that or know what could be going on ? Is there a way to "reset" without rebooting ?