title: ValueError: numpy.dtype has the wrong size, try recompiling
body: <p>I just installed pandas and statsmodels package on my python 2.7
  When I tried  "import pandas as pd", this error message comes out.
  Can anyone help? Thanks!!!</p>
  
  <pre><code>numpy.dtype has the wrong size, try recompiling
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
    File "C:\analytics\ext\python27\lib\site-packages\statsmodels-0.5.0-py2.7-win32.egg\statsmodels\formula\__init__.py",
  line 4, in &lt;module&gt;
      from formulatools import handle_formula_data
    File "C:\analytics\ext\python27\lib\site-packages\statsmodels-0.5.0-py2.7-win32.egg\statsmodels\formula\formulatools.p
  y", line 1, in &lt;module&gt;
      import statsmodels.tools.data as data_util
    File "C:\analytics\ext\python27\lib\site-packages\statsmodels-0.5.0-py2.7-win32.egg\statsmodels\tools\__init__.py", li
  ne 1, in &lt;module&gt;
      from tools import add_constant, categorical
    File "C:\analytics\ext\python27\lib\site-packages\statsmodels-0.5.0-py2.7-win32.egg\statsmodels\tools\tools.py", line
  14, in &lt;module&gt;
      from pandas import DataFrame
    File "C:\analytics\ext\python27\lib\site-packages\pandas\__init__.py", line 6, in &lt;module&gt;
      from . import hashtable, tslib, lib
    File "numpy.pxd", line 157, in init pandas.tslib (pandas\tslib.c:49133)
  ValueError: numpy.dtype has the wrong size, try recompiling
  </code></pre>