Had this issue.. figured out what's causing it... definitively.

I had an earlier version of python installed, and I created a pythonhome user variable: "c:\python24."

I'm now using Python 2.5, and that old variable was:
1.) Keeping me from opening the IDLE
2.) Keeping the console from finding the os module.  This is also the source of the import os error.

TO FIX:
- modify the pythonhome variable to your current version, or.. remove it.

-Dmark
www.dmarkphotography.com