In matplotlib 1.2.1, OSX 10.8.3, python 3.3, running this snippet of code (in ipython3):

indep = r_[-12:12.1:.1]
dep = sin(indep)
plot(indep,dep)

produces a plot with ugly, garbled axis ticks, pictured here:

No amount of xlim, xticks, or anything else fixes the tick labels. Plotting different data doesn't make a difference. Only a single digit ever appears in the tick labels, and the negative ticks are always messed up. I can't even get matplotlib.pyplot to work in a vanilla python3 shell; the Python app launches but no window is ever displayed. I use python 3.3 via homebrew, but this doesn't work even in the primary installation package.

No warnings are ever printed during this process, and nothing is logged.