downloaded pdf-documents are saved as pdf.html instead of simply pdf and that means that I can read the document only online. I noticed that the Data menu of Ubuntu 12.04 only offers the alternative to save the page instead of the alternative save a copy - that is what I was used to. Is that the problem of the version or settings of Firefox???
In Firefox (I'm using the version 19), you should have some kind of PDF reader. Instead of right-clicking and clicking