matplotlib crashes python interpretor, and no plotting appear

Hi,
I freshly installed pycharm, python2.7 and matplotlib on my laptop (new macbook pro, with Yosemite). I can run a python console in pycharm, but when I come to plot the simplest vector with matplotlib.pyplot, python crashes.  It opens a figure window, but does not display the vector as a graph. Everything get stock at this point.

Example of a simple code that crashes:

import matplotlib.pyplot as plt
plt.figure()
plt.plot([1.6, 2.7])

Does anyone have an idea for solving this apparent bug?

I wonder if it has anything to do with this setting:
Backend MacOSX is interactive backend. Turning interactive mode on.

Thanks.