This had happened to me once but in office 2007. It happened when I tried to open an older file type so It went into compatibility mode, which also changes the layout.
Not sure if its the same thing with office 2003 but go into options, advanced, and see if you can find something like compatibility options or layout.
Anyway if its not their your looking for some kind of option like that so snoop around all the options, views, and windows menus.