title: `ipython` tab autocomplete does not work on imported module
body: <p>Tab completion on IPython seems not to be working. For example,</p>
  
  <pre><code>import numpy
  numpy.&lt;tab&gt;
  </code></pre>
  
  <p>simply adds a tab.</p>
  
  <pre><code>import numpy
  num&lt;tab&gt;
  </code></pre>
  
  <p>just adds a tab, too. Could you please suggest some possible causes for this problem? I am running Windows 7 and Python 2.6.5.</p>