The recent Adobe Acrobat update has a new setting: Always open PDFs downloaded from the web.
This setting seems to have been turned on as a default. A few days ago, out of nowhere, each time I downloaded a pdf, Acrobat would pop up to show me the pdf. And I have Safari's option to open safe files turned off!
I did find this Acrobat option and turned it off, but turning this on without my permission is inexcusable. I don't even use Acrobat as my default pdf viewer. And for security reasons, I never have downloaded files opening automatically.
This is such bad behavior.