Strange crashes

[Igor Korot]

Hi, ALL,
I'm trying to develop a software with Python.
It uses multi threading.

For some unknown reason the program crashes on my employer's machine
but on mine it runs fine.

Exception in thread Thread-3:
Traceback (most recent call last):
  File "C:\Python27\lib\threading.py", line 552, in __bootstrap_inner
    self.run()
  File "C:/Users/Nides/Documents/GitHub/l2l_R/lib\model\workerthread.py",
line  39, in run
    data = self.func(self.args)
  File "C:/Users/Nides/Documents/GitHub/l2l_R/lib\controller\controller.py",
line 589, in do_filter
    return m.filter(query, query_result)
  File "C:/Users/Nides/Documents/GitHub/l2l_R/lib\model\model.py",
line 159, in filter
    res = dbm.find_events(query, qres)
  File "C:/Users/Nides/Documents/GitHub/l2l_R/lib\model\dbmanager.py",
line 258, in find_events
    res = self.check_query(query)
  File "C:/Users/Nides/Documents/GitHub/l2l_R/lib\model\dbmanager.py",
line 248, in check_query
    self._close_db()
  File "C:/Users/Nides/Documents/GitHub/l2l_R/lib\model\dbmanager.py",
line 65, in _close_db
    self.conn.commit()
ProgrammingError: SQLite objects created in a thread can only be used
in that same thread.The object was created in thread id 14260 and this
is thread id 9264

Now, I can't do anything about it since I can't reproduce it.
'
So my question is: what might be causing this?
I checked and we both have 1 processor. The only difference is I have
WinXP and he has Win7.

Where should I start looking for causes?

Thank you.