Just ran the example code linked here again for my own sanity:
http://docs.python.org/dev/library/concurrent.futures.html#processpoolexecutor-example

Exactly the same thing happened. Here is the Traceback:
Traceback (most recent call last):
  File "<string>", line 420, in run_nodebug
  File "<module1>", line 28, in <module>
  File "<module1>", line 24, in main
  File "C:\Python33\lib\concurrent\futures\_base.py", line 546, in result_iterator
    yield future.result()
  File "C:\Python33\lib\concurrent\futures\_base.py", line 399, in result
    return self.__get_result()
  File "C:\Python33\lib\concurrent\futures\_base.py", line 351, in __get_result
    raise self._exception
concurrent.futures.process.BrokenProcessPool: A process in the process pool was terminated abruptly while the future was running or pending.