Yes, "diff" is a unix program, and there are win32 ports available for free (cf. Cygwin, GNU, ATT Research Labs, among others); another unix program (also ported) is "paste", which would let you put the two files side-by-side.

Anyway, you've already compared the files, and they are the same. (I was afraid that might happen...) Maybe flyingmoose's more recent reply has the part you really need -- one can only hope. At least you've proven that there was no pollution of the data up to that point -- the problem involves one of the Tk modules.