I have a situation very much like the one at ImportError: DLL load failed: %1 is not a valid Win32 application, but the answer there isn\'t working for me.
My Python
In my case, I have 64bit python, and it was lxml that was the wrong version--I should have been using the x64 version of that as well. I solved this by downloading the 64-bit version of lxml here:
https://pypi.python.org/pypi/lxml/3.4.1
lxml-3.4.1.win-amd64-py2.7.exe
This was the simplest answer to a frustrating issue.