title: No module named _multiprocessing / requires pyzmq >= 2.1.11
body: <p>I have been looking exhaustively at the different error messages to try and resolve this, and I have run a number of reinstalls of both python 2.7 and ipython, but I just cannot get ipython notebook to launch. </p>
  
  <p>The <code>catch_config_error</code> in <code>application.py</code> would suggest an incorrect 'trait' setup, which is beyond my area of knowledge</p>
  
  <p>I am also very confused by the  <code>"IPython.html requires pyzmq &gt;= 2.1.11"</code> as <code>pip list</code> is showing version ~14</p>
  
  <p>i have a feeling I might have some PATH variables incorrectly setup, and there is a folder 
  csvn with a python25 folder in it?</p>
  
  <p>See error messages and pip log below</p>
  
  <p><code>Iptest</code> returns</p>
  
  <pre><code>Traceback (most recent call last):
  File "C:\csvn\Python25\lib\runpy.py", line 162, in _run_module_as_main
  "__main__", fname, loader, pkg_name)
  File "C:\csvn\Python25\lib\runpy.py", line 72, in _run_code
   exec code in run_globals
  File "C:\csvn\Python25\Scripts\iptest.exe\__main__.py", line 5, in &lt;module&gt;
  File "C:\csvn\Python25\lib\site-packages\IPython\testing\iptestcontroller.py",
  line 23, in &lt;module&gt;
  import multiprocessing.pool
   File "C:\csvn\Python25\lib\multiprocessing\__init__.py", line 83, in &lt;module&gt;
  import _multiprocessing
  ImportError: No module named _multiprocessing
  </code></pre>
  
  <p><code>Pip list</code> returns:</p>
  
  <pre><code>backports.ssl-match-hostname (3.4.0.2)
  certifi (14.05.14)
  distribute (0.6.49)
  docutils (0.12)
  eventlet (0.14.0)
  greenlet (0.4.2)
  ipython (2.1.0)
  Jinja2 (2.7.3)
  MarkupSafe (0.23)
  nose (1.3.3)
  numpydoc (0.5)
  pip (1.5.6)
  Pygments (1.6)
  pyreadline (2.0)
  pyzmq (14.3.1)
  setuptools (0.6c11)
  Sphinx (1.2.2)
  tornado (4.0)
  wsgiref (0.1.2)
  </code></pre>
  
  <p>and </p>
  
  <p><code>Ipython Notebook</code> returns</p>
  
  <pre><code>Traceback (most recent call last):
    File "C:\csvn\Python25\lib\runpy.py", line 162, in _run_module_as_main
      "__main__", fname, loader, pkg_name)
    File "C:\csvn\Python25\lib\runpy.py", line 72, in _run_code
      exec code in run_globals
    File "C:\csvn\Python25\Scripts\ipython.exe\__main__.py", line 9, in &lt;module&gt;
    File "C:\csvn\Python25\lib\site-packages\IPython\__init__.py", line 120, in st
  art_ipython
      return launch_new_instance(argv=argv, **kwargs)
    File "C:\csvn\Python25\lib\site-packages\IPython\config\application.py", line
  563, in launch_instance
      app.initialize(argv)
    File "&lt;string&gt;", line 2, in initialize
    File "C:\csvn\Python25\lib\site-packages\IPython\config\application.py", line
  92, in catch_config_error
      return method(app, *args, **kwargs)
    File "C:\csvn\Python25\lib\site-packages\IPython\terminal\ipapp.py", line 321,
   in initialize
      super(TerminalIPythonApp, self).initialize(argv)
    File "&lt;string&gt;", line 2, in initialize
    File "C:\csvn\Python25\lib\site-packages\IPython\config\application.py", line
  92, in catch_config_error
      return method(app, *args, **kwargs)
    File "C:\csvn\Python25\lib\site-packages\IPython\core\application.py", line 38
  1, in initialize
      self.parse_command_line(argv)
    File "C:\csvn\Python25\lib\site-packages\IPython\terminal\ipapp.py", line 316,
   in parse_command_line
      return super(TerminalIPythonApp, self).parse_command_line(argv)
    File "&lt;string&gt;", line 2, in parse_command_line
    File "C:\csvn\Python25\lib\site-packages\IPython\config\application.py", line
  92, in catch_config_error
      return method(app, *args, **kwargs)
    File "C:\csvn\Python25\lib\site-packages\IPython\config\application.py", line
  475, in parse_command_line
      return self.initialize_subcommand(subc, subargv)
    File "&lt;string&gt;", line 2, in initialize_subcommand
    File "C:\csvn\Python25\lib\site-packages\IPython\config\application.py", line
  92, in catch_config_error
      return method(app, *args, **kwargs)
    File "C:\csvn\Python25\lib\site-packages\IPython\config\application.py", line
  406, in initialize_subcommand
      subapp = import_item(subapp)
    File "C:\csvn\Python25\lib\site-packages\IPython\utils\importstring.py", line
  42, in import_item
      module = __import__(package, fromlist=[obj])
    File "C:\csvn\Python25\lib\site-packages\IPython\html\notebookapp.py", line 39
  , in &lt;module&gt;
      check_for_zmq('2.1.11', 'IPython.html')
    File "C:\csvn\Python25\lib\site-packages\IPython\utils\zmqrelated.py", line 37
  , in check_for_zmq
      raise ImportError("%s requires pyzmq &gt;= %s"%(required_by, minimum_version))
  ImportError: IPython.html requires pyzmq &gt;= 2.1.11
  </code></pre>