title: "ImportError: No module named" when trying to run Python script
body: <p>I'm trying to run a script that launches, amongst other things, a python script.  I get a ImportError: No module named ..., however, if I launch ipython and import the same module in the same way through the interpreter, the module is accepted.  </p>
  
  <p>What's going on, and how can I fix it?  I've tried to understand how python uses PYTHONPATH but I'm thoroughly confused.  Any help would greatly appreciated.  </p>