I've encountered a segmentation fault using the Agg backend when making and saving a png plot. The segmentation fault does not seem to occur under different backends (e.g. Cairo).
The sequence of commands amounts to making a plot, setting the limits of the plot, then saving the plot as a png using savefig. If the value of one of the points is too large, a segmentation fault is generated. Obviously the simple work-around is to not plot the out-of-bounds points, but the segmentation fault is probably not the desired behavior!
Below is an example, which generates a segmentation fault on matplotlib versions 0.99.0 (run on OS X 10.5.8) and 0.98.5.2 (run on Fedora 11 and CentOS 5.3).
Can others reproduce this issue?
if __name__ == '__main__':
xdata,ydata = scipy.rand(2,10)
xdata=1.0e9 # comment out to avoid seg fault