About two weeks ago, I could no longer open Office files (Word, Excel, PowerPoint) that were Outlook attachments. My machine (HP Envy) was running WIN 10 and Office 2013. This seemed to coincide with a regular WIN 10 update. I then upgraded to Office 2016. This did not fix the problem.
A workaround is to right click the file, save the file and then open it. This however is very awkward.
Currently as a work around I have "Enable Protected View for Outlook attachments" unchecked in the Trust Center under Protected View in the Office apps, but this is an insecure workaround.
I do not have this problem on my Surface Pro 3 running WIN 8.1 and Office 2013.
On-line searches have failed to reveal a satisfactory solution.
What caused this problem and how do I fix it.