I have a strange problem with my powered USB hub (USB 2.0) and my wired Apple keyboard which is plugged into that hub.
When I turn on the MacBook Pro (Early 2013), running OS X 10.9, the external keyboard is not working sometimes. As soon as I unplug the keyboard and plug it in again it works. This only happens when the MacBook has just turned on.
If I turn the powered hub to an unpowered hub (just by unplugging the power chord) the keyboard works fine - even at startup.
Does anyone have a clue what may be the problem?