Running WinPython-64bit-3.4.2.1\python-3.4.2.amd64 on a Win7 computer, "sphinx-build.exe" produces the following error:

Fatal error in launcher: Unable to create process using '"D:\Winpython\basedir34
\build\winpython-3.4.2.amd64\python-3.4.2.amd64\python.exe" "C:\WinPython-64bit-
3.4.2.1\python-3.4.2.amd64\Scripts\sphinx-build.exe" '

Since sphinx-build.exe is working fine on previous versions of WinPython, I assume this is a mistake in the parameter-setting in the build of the sphinx-build.exe