Try using ShellExView to disable all shell extensions, except the Microsoft and Opus ones, and after doing so fully exit Opus and then re-launch it.
I would start with the iCloud / Photo Stream shell extension(s) as it/they may be the cause of the problem even though they are "inactive". (It can't be fully inactive as if it was it would not appear in the tree at all.)
Another thing I suggest is removing all of your tabs (in case the problem is triggered by a particular file or folder) and opening Opus to show an empty folder (or at least not any folders containing video files, which are often triggers for bugs in third-party video codecs which Opus will call into to get details about video files). (Avoid the DropBox folder as well; the DropBox shell extension has been known to trigger problems in the past, although they've usually been solved by updating it.)