No graphics output
This kind of problem happens when you have both Numeric and numpy installed. This could be sometimes corrected by setting the appropriate "numerix" option in the $HOME/.matplotlib/matplotlibrc file like:
numerix : numpy
If you don't have the matplotlibrc file, you can copy it from /usr/lib64/python2.4/site-packages/matplotlib/mpl-data/matplotlibrc into
your $HOME/.matplotlib/ directory.