I've same issue with this one

Exception Type:     ImportError
Exception Value:    

DLL load failed: The specified module could not be found.

Exception Location:     C:\Python26\lib\site-packages\numpy\core\__init__.py in <module>, line 5
Python Executable:  C:\Program Files\Apache Software Foundation\Apache2.2\bin\httpd.exe
Python Version:     2.6.0
Python Path:    ['C:\\python26\\python26.zip', 'C:\\Python26\\Lib', 'C:\\Python26\\DLLs', 'C:\\Python26\\Lib\\lib-tk', 'C:\\Program Files\\Apache Software Foundation\\Apache2.2', 'C:\\Program Files\\Apache Software Foundation\\Apache2.2\\bin', 'C:\\Python26', 'C:\\Python26\\lib\\site-packages', 'c:/data/']
Server time:    Thu, 7 Jul 2011 22:39:09 -0700

Everything works fine on development atmosphere although not focusing on production atmosphere (exactly the same home windows machine however with apache and mod_wsgi).

my matplotlib code:

import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as plt
companies = (8,5,6,6,6)


ind = xrange(6)  # the x locations for the groups
width = 0.35       # the width of the bars
fig = plt.figure(figsize=(18,8))
plt.subplots_adjust(left=0.115, right=0.5,bottom=0.4)
ax = fig.add_subplot(111)
ax.bar(ind, companies, width, color='r')
filename = 'myfilename'
fig.savefig(os.path.join(settings.CHART_TEMP_PATH,filename))