Fix Python AMD64 installation:

Open regedit
Find Python in HKEY_LOCAL_MACHINE > SOFTWARE > PYTHON
Change the value of HKEY_LOCAL_MACHINE > SOFTWARE > PYTHON > PythonCore > 2.6 > PythonPath as C:\Python26\Lib;C:\Python26\DLLs;C:\Python26\Lib\lib-tk;C:\Python26\

Copy the entire HKEY_LOCAL_MACHINE > SOFTWARE > PYTHON key tree to HKEY_LOCAL_MACHINE > Wow6432Node

Source: http://www.mail-archive.com/distutils-sig@python.org/msg10512.html