Hello guys, I have following problem with my brand new MBP 15 late 2016: Since I updated the OS to 10.12.3. I receive the following message whenever I open any file on my Mac: "document1.pdf is damaged and can’t be opened. You should move it to the Trash." It is equal what kind of file I open, let it be .pdf .docx .jpeg - I always receive the message from above. However I can view the files by using preview with the blank key. I figured out, that it has to do with gatekeeper settings. When I change the settings from "App Store" to "App Store and verified developers" first the system does not save my selection and second I still can not open any file on my mac. I then found a way to disable gatekeeper by using following terminal command sudo spctl --master-disable and I am now able to open any of my files just like normal. But this is not a long term solution, since I want my mac to stay safe. Does anyone know what else I could do?