Well, on my Linux system, when I get that error, it happens when I do
an update of numpy, but fail to rebuild mpl.  Here is the order how I
build things: numpy, scipy, matplotlib.  I would imagine ipython goes

That has been my order as well.  How can I track down why the import of numpy.core.multiarray is  causing the problem?  And why would it cause a problem only when MPL is being imported, but not if I import it manually?

Originally, I tried to build the GitHub trunk version of numpy, but then abandoned that.  Since MPL is saying that it was built against the 20000... ABI rather than the 10000... ABI, is it possible the MPL is finding some other version of numpy lying around?  However, I'm pretty sure I deleted everything from the git numpy build.  How could I pinpoint which numpy libraries are being linked against in the MPL build?