来自mtrand import的NLTK pos_tag ImportError *

Question

当我运行此代码时，我收到错误（如下）：

import nltk
sentence = """At eight o'clock on Thursday morning"""
tokens = nltk.word_tokenize(sentence)
nltk.pos_tag(tokens)

追溯是：

Traceback (most recent call last):
  File "<pyshell#5>", line 1, in <module>
    nltk.pos_tag(tokens)
  File "C:\Python27\lib\site-packages\nltk\tag\__init__.py", line 99, in pos_tag
    tagger = load(_POS_TAGGER)
  File "C:\Python27\lib\site-packages\nltk\data.py", line 605, in load
    resource_val = pickle.load(_open(resource_url))
  File "C:\Python27\lib\site-packages\numpy\__init__.py", line 171, in <module>
    import random
  File "C:\Python27\lib\site-packages\numpy\random\__init__.py", line 99, in <module>
    from mtrand import *
ImportError: DLL load failed: The application has failed to start because its side-by-    side configuration is incorrect. Please see the application event log or use the command-line sxstrace.exe tool for more detail.

我正在运行带有IDLE的Python 2.7.4 64位，并且我在Windows 7上安装了numpy-1.7.1 64位。

mtrand导入有什么问题？谢谢你的帮助。