Here's an example error report. This one is generated by Dimension3D's Copy Material script, but any script that tries to use tkinter fails at the same place, line 38 in Tkinter.py.

I wonder if this is a 32 bit / 64 bit related problem? That's the only material difference between my two Windows 7 environments, and looking at Tkinter.py, it checks for a 32 bit system and if found, imports FixTk. I'm trying to understand what's going on in there. :)