Accidental clicking a wrong file with the viewer open results in the viewer window (loading) and Directory Opus not responsive. This seems to happen in this situation where
Hidden files are shown
a Microsoft Office temp file is around (~$xxxxx.doc or ~$xxxxx.docx)
and this file is clicked.
Based on the extention the Office Viewer is loaded in docsvw64.exe (Directory Opus Active Proxy). Killing this process keeps Directory Opus alive but without viewer.
It perhaps would be good to somehow monitor the viewer process and kill and restart it when it no longer is responding to polls.