Ignore the Preview Button
When you open a page for editing in FrontPage 2003, the bottom bar has four buttons: Design, Split, Code, and Preview. My advice is to ignore the Preview button.
The Preview view pane is notorious for displaying certain types of sites incorrectly. Some viewers might see black or white boxes over their navigation buttons (that happens when the designer uses a transparent GIF for the button graphic). Others might see parts of their web page in the wrong place (that happens with some CSS-based layouts). Links may not work, Flash movies may not work properly. Basically, the Preview view may make you think that your site is “broken” when it’s not.
So instead, get comfortable with the File > Preview in Browser command. PixelMill has support articles online to teach you how to use Preview in Browser, and how to add additional browsers to the selection list. Why waste your time in the Preview pane when you can see your site as it would actually look in a browser?
(And here’s some advance information… the next Microsoft products that will replace FrontPage have gotten rid of the Preview button altogether! So you might as well be ahead of the curve and ignore it now.)