Problem with a new install

Hello,

this is the first time I write here. I'm using Python + PyQt4 + matplotlib on Windows 7.
First, I installed Python 2.7 and the other packages. After some time I decided to go back to 2.6.
I removed any packages (with the uninstaller) and also any PATH entry.
Finally, I installed Python 2.6 and matplotlib.

Now when I execute a script that contain a matplotlib object I run into this error:

Traceback (most recent call last):
   File "C:\Users\Femtotech\Documents\Femtotech\Airlight\Photodiode array\Software\Photodiode Array Monitor\main.py", line 12, in <module>
     from matplotlib.backends.backend_qtagg import FigureCanvasQTAgg as FigureCanvas
   File "C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_qtagg.py", line 12, in <module>
     from backend_qt import qt, FigureManagerQT, FigureCanvasQT,\
   File "C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_qt.py", line 19, in <module>
     raise ImportError("Qt backend requires pyqt to be installed.")
ImportError: Qt backend requires pyqt to be installed.
>>>
*** Remote Interpreter Reinitialized ***
>>>
Traceback (most recent call last):
   File "C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_qt4.py", line 215, in resizeEvent
     self.draw()
   File "C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_qt4agg.py", line 130, in draw
     FigureCanvasAgg.draw(self)
   File "C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_agg.py", line 394, in draw
     self.figure.draw(self.renderer)
   File "C:\Development\Python26\lib\site-packages\matplotlib\artist.py", line 55, in draw_wrapper
     draw(artist, renderer, *args, **kwargs)
   File "C:\Development\Python26\lib\site-packages\matplotlib\figure.py", line 798, in draw
     func(*args)
   File "C:\Development\Python26\lib\site-packages\matplotlib\artist.py", line 55, in draw_wrapper
     draw(artist, renderer, *args, **kwargs)
   File "C:\Development\Python26\lib\site-packages\matplotlib\axes.py", line 1934, in draw
     a.draw(renderer)
   File "C:\Development\Python26\lib\site-packages\matplotlib\artist.py", line 55, in draw_wrapper
     draw(artist, renderer, *args, **kwargs)
   File "C:\Development\Python26\lib\site-packages\matplotlib\axis.py", line 1017, in draw
     tick.draw(renderer)
   File "C:\Development\Python26\lib\site-packages\matplotlib\artist.py", line 55, in draw_wrapper
     draw(artist, renderer, *args, **kwargs)
   File "C:\Development\Python26\lib\site-packages\matplotlib\axis.py", line 234, in draw
     self.label1.draw(renderer)
   File "C:\Development\Python26\lib\site-packages\matplotlib\artist.py", line 55, in draw_wrapper
     draw(artist, renderer, *args, **kwargs)
   File "C:\Development\Python26\lib\site-packages\matplotlib\text.py", line 524, in draw
     bbox, info = self._get_layout(renderer)
   File "C:\Development\Python26\lib\site-packages\matplotlib\text.py", line 298, in _get_layout
     ismath=False)
   File "C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_agg.py", line 180, in get_text_width_height_descent
     font = self._get_agg_font(prop)
   File "C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_agg.py", line 221, in _get_agg_font
     font = FT2Font(str(fname))
RuntimeError: Could not open facefile C:\Program Files (x86)\Python27\lib\site-packages\matplotlib\mpl-data\fonts\ttf\Vera.ttf; Cannot_Open_Resource

Traceback (most recent call last):
   File "C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_qt4agg.py", line 83, in paintEvent
     FigureCanvasAgg.draw(self)
   File "C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_agg.py", line 394, in draw
     self.figure.draw(self.renderer)

[cut]

   File "C:\Development\Python26\lib\site-packages\matplotlib\text.py", line 524, in draw
     bbox, info = self._get_layout(renderer)
   File "C:\Development\Python26\lib\site-packages\matplotlib\text.py", line 298, in _get_layout
     ismath=False)
   File "C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_agg.py", line 180, in get_text_width_height_descent
     font = self._get_agg_font(prop)
   File "C:\Development\Python26\lib\site-packages\matplotlib\backends\backend_agg.py", line 221, in _get_agg_font
     font = FT2Font(str(fname))
RuntimeError: Could not open facefile C:\Program Files (x86)\Python27\lib\site-packages\matplotlib\mpl-data\fonts\ttf\Vera.ttf; Cannot_Open_Resource

You see, "C:\Development\Python26" is the correct folder of the new installation but "C:\Program Files (x86)\Python27" was the older (and deleted) one.

I don't know how it still search in the old path. There are no entry of that folder in the PATH variable.

What should I do to fix the issue? I can't run any program that uses matplotlib anymore!

Thank in advance!
Marco