Although I have not seen this for a few years, I have encountered similar disconnections/freezes with third party USB and/or Bluetooth devices (both actually come through the USB channel) in the past. Refreshing the connection by unplugging and replugging the device often resulted in a temporary fix. A permanent fix involved one or more of the following:
  1. updating or removing a third party USB driver (not necessarily one that is used by the disconnecting device) or
  2. Removing another USB/Bluetooth connected device or
  3. Removing or replacing a failed/failing hub in the loop — the disconnecting device does not have to be connected through the hub or
  4. An update/upgrade to OS X
In my personal experience I have invariably found connecting directly to a USB port on the computer to be more reliable than going through any hub (the USB connector in the keyboard is a USB hub subject to failure independent of the keyboard itself).

This kind of problem is notoriously difficult to troubleshoot, because the fault cannot be reliably recreated on demand. The only reliable troubleshooting technique requires...
  1. Identifying all the devices and drivers associated with either USB or Bluetooth
  2. Removing ONE and ONLY ONE potential candidate at a time
  3. Thorough testing being sure to wait more than long enough for the problem to recur (if it was occuring every couple of days allow three or four days without failure before declaring a solution)
  4. Remember electronic components AGE and electrical values change, so a device that has worked and still works may begin to fail due to environmental fluctuations such as room termperature or even minor power fluctuations that occur when say an electric motor starts up somewhere on the premisis
  5. Patience and perseverance.

If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein