Actually, the swf was published in Flash 4 which is the default setting in SWiSHmax. I do have the option of publishing it in a later version if I want to but I have difficulty in accepting that this could be the cause. My reason being that the same swf is used on all the other pages and they have no problem. Plus, if I manually add back the www in the address bar and then reopen the page, the navbar works perfectly.

My guess is that there's something in the html code that's responsible but I cannot see it.