I have a MacBook Pro (early 2009), running El Capitan v. 10.11.6. Automatic updates from the apple store were installed last night and this morning, every app I try to open won't. I get the message "You can't open the application because it may be damaged or incomplete." I have a few files on my desktop, and if I click on them, the "damaged or incomplete" apps associated with them open just fine. The update installed last night was "Security Update 2016-003 Supplemental Update, Version 10.11.6, Installed Jan 19, 2017" This happened before (January 1st). Same scenario. Not sure what updates were installed then. A buddy helped me get things up and running. What we eventually did was: replace the hard drive and then copy back up files over from superduper and time machine. All good for the past 2.5 weeks.