Also,
Your version of powerpoint may be different than mine, but when I choose save as ... web file (htm, html), a Publish button appears. If I click on that, a dialog box appears with a Web Options button. Click this button, and under "Browsers", either choose the most inclusive option, or go ahead and choose the "IE6 or higher" option, but UNCHECK the box that says "Rely on VML for displaying graphics..." It's the VML that's killing the web page in non-IE browsers.