Thanks for sending the log.
I can't find anything definite, but one thing which stands out is the Box Sync shell extension. Activity from it is appearing throughout the log file, so it may be involved.
That shell extension is also written in .Net, which is more or less against the rules for Windows shell extensions (Microsoft's rules, not ours) and a very bad idea in general. That makes me suspect it even more, although it is still only suspicion and could turn out to be completely innocent.
I recommend using ShellExView to disable any shell extensions related to Box, then fully exit Opus (via File / Exit Directory Opus) and see if the problem is still there.
If it is still there, it may be worth doing the same with other shell extensions, in case they are involved. (You can usually ignore the Microsoft ones, which normally only leaves a handful that need to be checked.)