Windows 8.1 and Dopus 11.5. If I double click a Word 2013 .DOC it opens the file then a dialogue box comes up and says 'Microsoft Word has stopped working' but it opens satisfactorily from File Explorer. Why is this? I would hate to go back to File Explorer.
If you have the preview pane open, please try closing it to see if that helps. I've seen reports that it can help in Explorer with similar problems.
Since it is Word that is crashing after Opus has asked it to open a file, there isn't a lot we can do ourselves, since Opus is out of the picture by the time the crash in Word happens, but these Word troubleshooting steps seemed to help people with similar problems in Explorer:
(I am not sure if all parts of the article apply to Office 2013, but parts of it mention Office 2013 and have been updated for it, at least.)
As a workaround, you may be able to avoid the problem by editing the .DOC / .DOCX filetypes in Opus (Settings > File Types) and assigning Left Double-Click events to them which run:
"\Word.exe" {filepath$}
That will override what happens when you double-click the documents in Opus (without affecting any other programs), and make it so Word.exe is run with the path to the file on the command line, which is the most simple way to launch the files in Word. (The default method probably uses DDE, which can be more fragile.)