Summarizing other messages, it seems that tkinter is intended to be thread-safe (as long tk.mainloop is started in the tk thread) and mostly is until it is not (probably from timing issue). With fresh 2.7.8 install, I ran TkinterCrash2.py. I got the following twice:

Exception in thread Thread-12:
Traceback (most recent call last):
  File "C:\Programs\Python27\lib\threading.py", line 810, in __bootstrap_inner
    self.run()
  File "tkcrash2.py", line 49, in run
    self.deliverToQueue((self.target, z, y))
  File "tkcrash2.py", line 131, in arrival_122
    new_yz[1])
  File "C:\Programs\Python27\lib\lib-tk\Tkinter.py", line 2282, in create_line
    return self._create('line', args, kw)
  File "C:\Programs\Python27\lib\lib-tk\Tkinter.py", line 2270, in _create
    *(args + self._options(cnf, kw))))
ValueError: invalid literal for int() with base 10: 'None'

and the progrm continued. After another 100-200 launches, I tried to close the tk window and got the "python has stopped working" message from Windows. After this, every time I restart, I soon got the message again. Something seems to have been altered, though I do not see a relevant process in task manager.

I closed and reopened the command prompt process and restarted with pythonw instead of python and the program ran until too sluggish to continue. I then closed and reran and got 'pythonw has stopped working' at about launch 5. Third time ran until I closed at 50 launches. Fourth time stopped after 10 launches.

Serhiy, have any fresh insight?