in my extension I am using xml.dom.minidom to parse an xml document.
Importing the needed functionality works on mac, but not on windows.

On Mac:

import xml
from xml.dom import expatbuilder

On Windows:

import xml
from xml.dom import expatbuilder
Traceback (most recent call last):
File "<console>", line 1, in <module>
File "C:\Program Files (x86)\Slicer
4.1.0-2012-07-28\lib\Python\Lib\xml\dom\expatbuilder.py", line 32, in
<module>
from xml.parsers import expat
File "C:\Program Files (x86)\Slicer
4.1.0-2012-07-28\lib\Python\Lib\xml\parsers\expat.py", line 4, in
<module>
from pyexpat import *
ImportError: No module named pyexpat