I think the problem might be related to using numarray and not numpy.
matplotlib is not heavily tested (if at all) on anything but numpy anymore.
See this from your output log:
D:\Program
Files\Python-2.5.1\Lib\site-packages\matplotlib\numerix\__init__.py:65:
DeprecationWarning: numarray use
Hello i' am an newbie in matplotlib and python!
I've installed python 2.5.1 + numpy 1.0.4 + numarray 1.5.2 but have many
problems !
I've written an easy plot script
import matplotlib
import pylab
from pylab import arange,sin,pi,plot,xlabel,ylabel,title,grid,show,axis
ymax = max([1,4,9,16,12,5,7,1