title: matplotlib 1.3.0 ImportError: DLL load failed: %1 is not a valid Win32 application
body: <p>I have 2 pc (laptop and workstation), when I run code for version check I get on laptop:</p>
  
  <pre><code>computer
  LAPTOP
  OS props
  Windows-7-6.1.7601-SP1
  python props
  ('default', 'May 15 2013 22:44:16')
  python version
  2.7.5
  OS bit and OS type
  ('64bit', 'WindowsPE')
  check if system is 32bit or 64bit
  ('7fffffffffffffff', True)
  numpy version
  1.7.1
  matplotlib version
  1.3.0
  </code></pre>
  
  <p>and on workstation:</p>
  
  <pre><code>computer
  WORKSTATION
  OS props
  Windows-7-6.1.7601-SP1
  python props
  ('default', 'May 15 2013 22:44:16')
  python version
  2.7.5
  OS bit and OS type
  ('64bit', 'WindowsPE')
  check if system is 32bit or 64bit
  ('7fffffffffffffff', True)
  numpy version
  1.7.1
  matplotlib version
  1.3.0
  </code></pre>
  
  <p>the software is mainly the same except some additional packages. But when I try to run the following code on the workstation computer:</p>
  
  <pre><code>import numpy as np
  import matplotlib
  # matplotlib.use('QTAgg')
  from matplotlib import pyplot as plt
  </code></pre>
  
  <p>I get the following error:</p>
  
  <pre><code>Traceback (most recent call last):
    File "C:\Users\WORKSTATION\python\src\gibljiv_kontakt_E11_vzmet\preview_and_sort_measurement_data.py", line 9, in &lt;module&gt;
      from matplotlib import pyplot as plt
    File "C:\Python27\lib\site-packages\matplotlib\pyplot.py", line 98, in &lt;module&gt;
      _backend_mod, new_figure_manager, draw_if_interactive, _show = pylab_setup()
    File "C:\Python27\lib\site-packages\matplotlib\backends\__init__.py", line 28, in pylab_setup
      globals(),locals(),[backend_name],0)
    File "C:\Python27\lib\site-packages\matplotlib\backends\backend_tkagg.py", line 8, in &lt;module&gt;
      import Tkinter as Tk, FileDialog
    File "C:\Python27\lib\lib-tk\Tkinter.py", line 38, in &lt;module&gt;
      import FixTk
    File "C:\Python27\lib\lib-tk\FixTk.py", line 65, in &lt;module&gt;
      import _tkinter
  ImportError: DLL load failed: %1 is not a valid Win32 application
  </code></pre>
  
  <p>I would like to know what is wrong and how can this be repaired? The code works (it does not return any error) if I uncomment the line:</p>
  
  <p>matplotlib.use('QTAgg')</p>
  
  <p>but as I use this for showing plots no plots are shown. Any suggestions what is wrong and how to fix this. 
  I would like to add, that like a month ago before I updated python and python's packages on my workstation computer the matplotlib was working without problems, but now I get this error.</p>