My employer uses a training and document system (third party) that requires the use of Acrobat to view PDFs. I never have to fill out forms within the PDFs; I simply can't open the files via Preview (or Firefox). Apparently the provider inserts JavaScript into the published documents (which, I assume, track document usage, since it is a training system).

Also, I can't post a link to the document, since it contains proprietary training materials.