My computer often loses communication with USB devices, and no hardware changed - the only thing that happened was an upgrade to Mavericks.USB devices -> D-Link hub -> Gefen KVM -> 2008-era Mac Pro.
I am having this problem. I don't have a USB hub. I plug the KVM into two USB ports on my Mac Pro (Early 2008) and the other three USB ports stop working altogether. If I unplug the KVM, all USB ports work fine. I am not sure I can blame Mavericks. My 2009 iMac with Mavericks has the KVM plugged in and its one free USB port works fine. It has something to do with power management on the Mac Pro.