[Python] ValueError: numpy.dtype has the wrong size, try recompiling

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?

numpy.dtype has the wrong size, try recompiling
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "C:\analytics\ext\python27\lib\site-packages\statsmodels-0.5.0-py2.7-win32.egg\statsmodels\formula\__init__.py",
line 4, in <module>
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 <module>
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 <module>
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 <module>
from pandas import DataFrame
File "C:\analytics\ext\python27\lib\site-packages\pandas\__init__.py", line 6, in <module>
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

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