Hi Hilary,
I´m sorry but I can´t do that because it´s a huge form for a customer of mine. I don´t think that they would agree if I make that form public.
It can´t be a sharepoint issue I think because I published another form to that library and there, all the expression boxes were read only as they should be.
What I can additionally tell you is that ALL my fields can be edited when opening my form from the sharepoint. For example: If I click on a picture or file attachment field that has an picture allready assigned to it, I am prompted to choose and paste a picture file. And I´m not in design mode. I open my form from the sharepoint library. Perhaps it´s a general infopath setting that I have to change!? I´m opening my forms with infopath itself (client app). Not with the Internet Explorer.
I don´t know what to do. Cant anybody help me :(