Quick question.... what happens in each of the suspect problem browsers if you call the .swf file directly instead of embedded in an HTML page?... If the files work correctly in that situation, you will probably need to google "SWFobject". This is used for standard embedding in HTML pages and allows for multi browser functionality. Other than that, a google search should reveal numerous fixes for this issue as it is a regularly posted problem.
A mind once stretched by a new idea never regains its original dimensions.
- Oliver Wendell Holmes