Can't run ./configure at installation

[Ben Tay]

Hi,

I'm trying to install a new version of PETSc into windows using cygwin. 
I met with the following error at installation:

$ ./config/configure.py --with-cc='win32fe cl' --with-fc='win32fe f90' 
--download-f-blas-lapack=1 LIBS="-L'/cygdrive/c/Program Files/Microsoft 
Visual Studio/DF98/LIB'"


'import site' failed; use -v for traceback
Traceback (most recent call last):
  File "./config/configure.py", line 2, in <module>
    import os
ImportError: No module named os

May I know why is this happening?

Thank you very much.

Regards.