On a windows PC with several Python Versions installed (but only one used) i got a problem when executing python3.4 applications:

   File "C:\Python34\lib\site.py", line 176

What to do? Because python.exe is pointing to python3.4:

C:\test>which python.exe

One solution could be to check if the filetype assosciations are correct and change them if they are not. Run as Administrator:

C:\Users\User>ftype Python.CompiledFile="C:\Python34\python.exe" "%1" %*
Python.CompiledFile="C:\Python34\python.exe" "%1" %*

C:\Users\User>ftype Python.File="C:\Python34\python.exe" "%1" %*
Python.File="C:\Python34\python.exe" "%1" %*

C:\Users\User>ftype Python.NoConFile="C:\Python34\pythonw.exe" "%1" %*
Python.NoConFile="C:\Python34\pythonw.exe" "%1" %*