I have been experiencing sleep issues (really waking from sleep) when my USB 3.0 Hub has been plugged in. I bought the Uspeed USB 3.0 7 Port Hub for my late 2012 iMac. If I leave my iMac and let it go to sleep for an extended period of time (usually 3-8+ hours) when I return my screen freezes for about 30+ seconds or so, after that everything works fine. If I unplug the hub, everything works fine and starts up instantly. So obviously it's the hub. Any ideas?