Page content doesn't display when opening existing page from a remote server.

I am trying to update a page (.PHP) from an existing, older website.  Upon opening, no content or code is displayed...the application suggests that the page includes "dynamically linked content" and asks if I would like it to open, I click "yes" and a progress bar at the top just endlessly appears to spin.   NOTHING HAPPENS and it appears to freeze the file, so I have to force-cancel the application.   This is by no means a complicated page I'm trying to edit...it has some CSS, a nav menu and an accordion containing the data I need to edit.    Using a MAC.   Please help?!!??!!