PowerPoint presentations won't open on mac but I can see their preview on Finder. It says password-protected but it is NOT password-protected Below is the powerpoint presentation I am trying to view. I can see it through Finder, as you can see below, but when I try to open it on OpenOffice or LibreOffice I get the dialog below. Again this file is not password-protected in any way, it is just one of those powerpoint presentations that people send by email.

Any ideas?
It's shown because Preview can open PowerPoint files in view only mode; so I suppose you can open it with Preview.