Error codes mean very little.
What's more important is what is happening and what your are doing when it's happening.
If you are saying that the program won't even launch, for instance, that's one issue. If the program launches but crashes as soon as you add media to it, that's another issue.
What are you doing when it stops working?
In fact the program does not launch, and I just realized that even Photoshop Elements is doing exactly the same (again Error 16). The only difference was that I had updated Yosemite. My guess is that the update is not compatible with Premiere and Photoshop 13 elements. It happened before with other Apple updates and previous versions of Premiere and Photoshop. I was trying to get in touch with someone at Adobe but I only could find the community.
I don't think that's it. I updated my Mac to Yosemite and my versions 11, 12 and 13 work fine.
Have you updated your Premiere Elements and Photoshop Elements to version 13.1?
No, I will try. I am surprised: version 12 did not work with Yosemite, and I had to buy 13.
Something else must be going on, Gianluigi. As I've said, my versions 11 and 12 also work just fine on Yosemite.