Opening a publisher document that was just recently authored on my own machine results in a ‘Publisher has detected a problem in the file you are trying to open. To protect your computer, Publisher will not open the file.‘
My immediate thought is something happened to the file, luckily I have it sync with Google Drive. Restore the previous version and same issue. I still don’t know what is triggering the message but the workaround is adding a registry key.
Adding the key shown above does not remove the protection merely lets you make the decision to continue opening the document or not. Without this key you are presented with only an ‘Ok’ button and the document will never open.