I have an IS710 with the same flash problem. It does not always go off even when set to do so but other times it works fine. I can tell because the little orange light above the view finder does not light up (indicating it is charging the flash) when this problem occurs. It is due to a reported problem with the camera. I think some other models have the same issue. I internet researched it over a year ago and other owners were reporting the same issue.