wxPython error "can't set focus to invalid window"

[omission9]

rus20376 at salemstate.edu (omission9) wrote in message news:<defa238f.0402100756.2433455f at posting.google.com>...
> An application I have written is, suddenly it seems, throwing the
> following error after being left in use for several hours. This does
> not seem to occur with lighter usage. I am not 100% sure what causes
> this? Anyone have any advice? Seen it before?
> 
> Traceback (most recent call last):
>   File "PythonCardPrototype\binding.pyo", line 304, in _dispatch
>   File "wxPython\events.pyo", line 23, in GetEventType
> wxPython.wxc.wxPyAssertionError: C++ assertion "wxAssertFailure"
> failed in e:\Projects\wx2.4\src\msw\window.cpp(454): can't set focus
> to invalid window


To clarify this further this seems to occur when the application has
been left running for several hours and the application has been
minimized to the Windows task bar. The error happens when the user
tries to maximize the window. The application has a child thread
running(simply polls a dircetory and processes some text files) in the
background.
Does this help jog anyone's memory of what his could be? Blame
windows? ;)