I am experiencing the problems that have been described in this thread. It only started happening as a problem yesterday. My machine is x64, Windows 10, and I have Office 2016 installed.
I have to save all attachments and unblock them in order to be able to open them. Office files saved from the web also required this.
Double-clicking an attachment in an email results in various messages, for example:
- Protected view has stopped working
- PowerPoint found a problem with content in <filename>
When I tried opening an Excel file downloaded from the internet the launch window just hung and I had to force it to close.
I've followed the instructions to get to the Trust Center but there was no option for Protected View in Outlook.
I could access the option via other Office programs and have been able to turn off settings. At first it didn't seem to save the settings but I've closed all Ofice programs, redone the changes and they seem to have stuck.
However, Outlook still wants to open every attachment in protected mode, and is failing to do so.
The Trust Center in Outlook does have an Attachment Handling area, with Attachment Security Mode set to Default. I can't find anywhere to change this.
The ideal resolution is a fix to protected mode crashing, but I'd be happy with knowing how to change the security mode.