wxPython wxProgressDialog randomly skips

Question

Strange problem - I'm using wxPython version 2.8 with Python version 2.6. I'm inserting thousands of records into a database and using wxProgressDialog.Update to keep up with the status of the process. The code looks like this:

    (keepgoing, skip) = self.frame.dialog.Update(prog,
                                                 msg + "\n" + txt)
    if not keepgoing:
        raise UserAborted
    if skip:
        raise UserSkipped

On my laptop, this works as intended. But on my Asus netbook, it seems to randomly raise the UserSkipped exception anyway - even when I remove the skip button from the dialog completely. Strangely, it's (I say randomly only because I have no idea why this would happen) returning True for the second value. If I catch the error and allow the process to continue, it will keep going and at randomly intervals will raise the same exception, over and over.

Any idea why this would happen?