No module named os

[smitty at home.com]

'import site' failed; use -v for traceback
Traceback (most recent call last):
  File "./setup.py", line 3, in <module>
    import sys, os, glob
ImportError: No module named os


I'm trying to build a small program and I get the above error.
I have had this error popup in the past while trying to build other
programs. What can I do?

Thanks