title: kernal keeps on dying in jupyter notebook when opening a notebook
body: <p>When opening any jupyter notebook, even one with no code in, I get the 'Dead kernal' message:</p>
  
  <blockquote>
    <p>The kernel has died, and the automatic restart has failed. It is possible the kernel cannot be restarted. If you are not able to restart the kernel, you will still be able to save the notebook, but running code will no longer work until the notebook is reopened.</p>
  </blockquote>
  
  <p>The error seems to be the following (taken from the terminal window):</p>
  
  <blockquote>
    <p>TypeError: metaclass conflict: the metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its bases</p>
  </blockquote>
  
  <p>I have tried pip uninstalling and pip installing jupyter but I am still getting the same error.</p>
  
  <p>Operating system: macOS Sierra Version 10.12.1,
  Python version: conda 4.1.11 </p>
  
  <p>Help would be very welcome!</p>