Google App Engine Deploy AttributeError expat_CAPI - google-app-engine

Question

I have been using Google App Engine Launcher many times and it worked perfect but recently I used it and I had this Error:
2014-01-02 18:50:58 Running command: "[u'C:\\Python27\\python.exe', '-u', u'C:\\Program Files (x86)\\Google\\google_appengine\\appcfg.py', '--no_cookies', u'--email=[my email]', '--passin', 'update', u'D:\\temp\\my-aiesec']"
Traceback (most recent call last):
File "C:\Program Files (x86)\Google\google_appengine\appcfg.py", line 196, in <module>
run_file(__file__, globals())
File "C:\Program Files (x86)\Google\google_appengine\appcfg.py", line 192, in run_file
execfile(script_path, globals_)
File "C:\Program Files (x86)\Google\google_appengine\google\appengine\tools\appcfg.py", line 81, in <module>
from google.appengine.tools import bulkloader
File "C:\Program Files (x86)\Google\google_appengine\google\appengine\tools\bulkloader.py", line 128, in <module>
from google.appengine.ext.bulkload import bulkloader_config
File "C:\Program Files (x86)\Google\google_appengine\google\appengine\ext\bulkload\bulkloader_config.py", line 47, in <module>
from google.appengine.ext.bulkload import simplexml_connector
File "C:\Program Files (x86)\Google\google_appengine\google\appengine\ext\bulkload\simplexml_connector.py", line 40, in <module>
from xml.etree import cElementTree as ElementTree
File "C:\Python27\Lib\xml\etree\cElementTree.py", line 3, in <module>
from _elementtree import *
AttributeError: 'module' object has no attribute 'expat_CAPI'
2014-01-02 18:50:59 (Process exited with code 1)
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1- First I thought the version of my GAE is out dated. so I upgrade to newest version 1.8.8.
2- I set the python 2.7 path in preferences.
3- I created a new project and launched it locally and it worked.
But still I had this deploying problem.

Answer 1

Previously I defined PYTHONPATH in the Environment Variables (System Variables) of my windows. I removed that Variable and Google App Engine worked again.