DO is keeping files open

never had issue before, but occassionally but daily, i try to open a file in an app that I had browsed to with DO, and the app reports that file is open. IZf i close DO, I can open the file.

Which file types are involved?

It's usually (although not always) not Opus itself, but a thumbnailer or shell extension which ran inside of dopus.exe but is part of something else. (e.g. With video files, some thumbnailers, or the codecs/demuxers they use in turn, will leave a file locked if they run into problems parsing the file to generate a thumbnail. Updating or replacing them usually fixes the issue, but the first step is tracking down the type of file involved.)