SciPy 0.12.0 and Numpy 1.6.1 - numpy.core.multiarray failed to import
numpy, python, scipy
Solution
So it seems that the cause of the error was incompatibility between scipy 0.12.0 and the much older numpy 1.6.1.
There are two ways to fix this - either to upgrade numpy (to ~1.7.1) or to downgrade scipy (to ~0.10.1).
If ArcGIS 10.2 specifically requires Numpy 1.6.1, the easiest option is to downgrade scipy.
Problem
I just installed ArcGIS v10.2 64bit background processing which installs Python 2.7.3 64bit and NumPy 1.6.1. I installed SciPy 0.12.0 64bit to the same Python installation. When I opened my Python interpreter I was able to successfully `import arcpy, numpy, and scipy`. However, when I tried to `import scipy.ndimage` I got an error that said `numpy.core.multiarray failed to import`. Everything I have found online related to this error references issues between `scipy` and `numpy` and suggest upgrading to `numpy 1.6.1`. I'm already at `numpy 1.6.1`. Any ideas how to deal with this?