title: ipython notebook freeze on start
body: <p>my ipython notebook functionality stop working. 
  If I do</p>
  
  <p>ipython notebook</p>
  
  <p>the console just hangs forever with no debug output.
  I have already tried reinstalling ipython but no success. 
  Also, if I start normal ipython everything seems fine.</p>
  
  <p>Does anybody have a clue how to solve this? I suspect some lock file is still there but how can I find out what is exactly going wrong? </p>
  
  <p>also if I force interrupt I get the following stack trace</p>
  
  <pre><code>^C^CTraceback (most recent call last):
    File "/home/lfiaschi/anaconda/bin/ipython", line 9, in &lt;module&gt;
      load_entry_point('ipython==1.2.1', 'console_scripts', 'ipython')()
    File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/IPython/__init__.py", line 118, in start_ipython
      return launch_new_instance(argv=argv, **kwargs)
    File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/IPython/config/application.py", line 544, in launch_instance
      app.initialize(argv)
    File "&lt;string&gt;", line 2, in initialize
    File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/IPython/config/application.py", line 89, in catch_config_error
      return method(app, *args, **kwargs)
    File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/IPython/terminal/ipapp.py", line 312, in initialize
      super(TerminalIPythonApp, self).initialize(argv)
    File "&lt;string&gt;", line 2, in initialize
    File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/IPython/config/application.py", line 89, in catch_config_error
      return method(app, *args, **kwargs)
    File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/IPython/core/application.py", line 373, in initialize
      self.parse_command_line(argv)
    File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/IPython/terminal/ipapp.py", line 307, in parse_command_line
      return super(TerminalIPythonApp, self).parse_command_line(argv)
    File "&lt;string&gt;", line 2, in parse_command_line
    File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/IPython/config/application.py", line 89, in catch_config_error
      return method(app, *args, **kwargs)
    File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/IPython/config/application.py", line 474, in parse_command_line
      return self.initialize_subcommand(subc, subargv)
    File "&lt;string&gt;", line 2, in initialize_subcommand
    File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/IPython/config/application.py", line 89, in catch_config_error
      return method(app, *args, **kwargs)
    File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/IPython/config/application.py", line 405, in initialize_subcommand
      subapp = import_item(subapp)
    File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/IPython/utils/importstring.py", line 42, in import_item
      module = __import__(package, fromlist=[obj])
    File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/IPython/html/notebookapp.py", line 64, in &lt;module&gt;
      from .services.kernels.kernelmanager import MappingKernelManager
    File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/IPython/html/services/kernels/kernelmanager.py", line 21, in &lt;module&gt;
      from IPython.kernel.multikernelmanager import MultiKernelManager
    File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/IPython/kernel/__init__.py", line 6, in &lt;module&gt;
      from .connect import *
    File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/IPython/kernel/connect.py", line 39, in &lt;module&gt;
      from IPython.utils.localinterfaces import LOCALHOST
    File "/home/lfiaschi/anaconda/lib/python2.7/site-packages/IPython/utils/localinterfaces.py", line 43, in &lt;module&gt;
      PUBLIC_IPS = socket.gethostbyname_ex(socket.gethostname() + '.local')[2]
  KeyboardInterrupt
  </code></pre>