Cant't get this right... Plz help

I’m making a site in dreamweaver, with a flash menu. on that flash menu I have buttons that load a external text file and applies CSS to it before showing it. All this is well, BUT, the site is in Norwegian, and some of the letters that is typical of the Norwegian alphabet won’t show,( it’s just boxes)
and some of the nearby letters dissapear to.
Do anyone know what is causing this?
Wery greatfull for any help I might get…