problems converting glyph to bitmap

Python 2.3.4 (#1, Feb 2 2005, 12:11:53)
[GCC 3.4.2 20041017 (Red Hat 3.4.2-6.fc3)] on linux2
Type "help", "copyright", "credits" or "license" for more information.

from pylab import *
from data_helper import get_daily_data

Traceback (most recent call last):
  File "<stdin>", line 1, in ?
ImportError: No module named data_helper

intc, msft = get_daily_data()

Traceback (most recent call last):
  File "<stdin>", line 1, in ?
NameError: name 'get_daily_data' is not defined

delta1 = diff(intc.open)/intc.open[0]

Traceback (most recent call last):
  File "<stdin>", line 1, in ?
NameError: name 'intc' is not defined

# size in points ^2

... volume = (15*intc.volume[:-2]/intc.volume[0])**2
Traceback (most recent call last):
  File "<stdin>", line 2, in ?
NameError: name 'intc' is not defined

close = 0.003*intc.close[:-2]/0.003*intc.open[:-2]

Traceback (most recent call last):
  File "<stdin>", line 1, in ?
NameError: name 'intc' is not defined

scatter(delta1[:-1], delta1[1:], c=close, s=volume, alpha=0.75)

Traceback (most recent call last):
  File "<stdin>", line 1, in ?
NameError: name 'delta1' is not defined

ticks = arange(-0.06, 0.061, 0.02)
xticks(ticks)

([<matplotlib.axis.XTick instance at 0xb7c8bf4c>, <matplotlib.axis.XTick instance at 0xb7f0eccc>, <matplotlib.axis.XTick instance at 0xb6fea52c>, <matplotlib.axis.XTick instance at 0xb6feaa4c>, <matplotlib.axis.XTick instance at 0xb6feaf6c>, <matplotlib.axis.XTick instance at 0xb6f764ac>, <matplotlib.axis.XTick instance at 0xb6f769cc>], <a list of 7 Text xticklabel objects>)

yticks(ticks)

([<matplotlib.axis.YTick instance at 0xb7693f6c>, <matplotlib.axis.YTick instance at 0xb6f76f2c>, <matplotlib.axis.YTick instance at 0xb6f7944c>, <matplotlib.axis.YTick instance at 0xb6f7996c>, <matplotlib.axis.YTick instance at 0xb6f79e8c>, <matplotlib.axis.YTick instance at 0xb6f7e3cc>, <matplotlib.axis.YTick instance at 0xb6f7e8ec>], <a list of 7 Text yticklabel objects>)

xlabel(r'$\Delta_i$', fontsize=20)

<matplotlib.text.Text instance at 0xb7f0edcc>

ylabel(r'$\Delta_{i+1}$', fontsize=20)

<matplotlib.text.Text instance at 0xb7c8d42c>

title('Volume and percent change')

<matplotlib.text.Text instance at 0xb6fe2ecc>

grid(True)

show()

Traceback (most recent call last):
  File "/usr/lib/python2.3/site-packages/matplotlib/backends/backend_gtk.py", line 318, in expose_event
    self._render_figure(self._pixmap, w, h)
  File "/usr/lib/python2.3/site-packages/matplotlib/backends/backend_gtkagg.py", line 70, in _render_figure
    FigureCanvasAgg.draw(self)
  File "/usr/lib/python2.3/site-packages/matplotlib/backends/backend_agg.py", line 382, in draw
    self.figure.draw(renderer)
  File "/usr/lib/python2.3/site-packages/matplotlib/figure.py", line 520, in draw
    for a in self.axes: a.draw(renderer)
  File "/usr/lib/python2.3/site-packages/matplotlib/axes.py", line 1412, in draw
    self.xaxis.draw(renderer)
  File "/usr/lib/python2.3/site-packages/matplotlib/axis.py", line 595, in draw
    self.label.draw(renderer)
  File "/usr/lib/python2.3/site-packages/matplotlib/text.py", line 336, in draw
    bbox, info = self._get_layout(renderer)
  File "/usr/lib/python2.3/site-packages/matplotlib/text.py", line 185, in _get_layout
    w,h = renderer.get_text_width_height(
  File "/usr/lib/python2.3/site-packages/matplotlib/backends/backend_agg.py", line 246, in get_text_width_height
    width, height, fonts = math_parse_s_ft2font(
  File "/usr/lib/python2.3/site-packages/matplotlib/mathtext.py", line 1232, in math_parse_s_ft2font
    handler.expr.render()
  File "/usr/lib/python2.3/site-packages/matplotlib/mathtext.py", line 892, in render
    self.elements[0].render()
  File "/usr/lib/python2.3/site-packages/matplotlib/mathtext.py", line 827, in render
    Element.render(self)
  File "/usr/lib/python2.3/site-packages/matplotlib/mathtext.py", line 657, in render
    element.render()
  File "/usr/lib/python2.3/site-packages/matplotlib/mathtext.py", line 830, in render
    self.font, self.sym, self.fontsize, self.dpi)
  File "/usr/lib/python2.3/site-packages/matplotlib/mathtext.py", line 460, in render
    cmfont.draw_glyph_to_bitmap(
RuntimeError: Could not convert glyph to bitmap