I'm getting access violations while resizing the window/splitters of the attached script. The problem is intermittant.
BTW, the embedding_in_wx4 example (among others) exhibits the same problem for me. I can always reproduce it by launching and resizing the window from small to large, without ever releasing the mouse button. This usually crashes within 10 resizes or so, but as with your description it's intermittent, it can take longer. This is with Windows XP, Python 2.3.4, matplotlib 0.61.0, wxPython 220.127.116.11. It was also present in the last matplotlib and wxPython releases at least. I seem to remember the plain wx frontend also being flaky under this kind of 'abuse', but I can't seem to get that to break now.
I also notice that you get a shear effect on some of the resizes (where the plot is drawn as a parallelogram). That's reproducible by shrinking the plot very small, but also occasionally happens at other sizes. I can't be sure whether the size/aspect ratio of the window causes that.