Suggestion: make a toy script (or comment out bunches of stuff) so you have a program which only reads from the data and prints it. See if it works right on the "other" machine, under those circumstances.

Write a toy program which just calls unpack on some literal data (not read from anywhere) and prints the results. See if it works the same on each machine.

When you get something that doesn't work the same on all machines, come back and post just the stuff that works differently, and we should be able to enlighten.

—John