The code is this: <html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns="http://www.w3.org/TR/REC-html40">
That's why it keeps reappearing. FP just puts it back.
Remember what I said about text boxes? Same applies to Word Art and anything else that has a convenient button on the Drawing Toolbar. Other browsers don't know what to do with it.
Turn the toolbar off in View>Toolbars or never ever click anything on it.