I'm Kevin and I am new to the forum, but I'm having the same problem - even though I've disabled the desktop double-click behaviour in Fences, the desktop double-click in Directory Opus 11 Pro doesn't work. Using Windows 8.1, i5 3470, 8 Gig RAM, 2 TB HD, NVidia GT660 graphics, running, Fences 2.12, Object Dock, Window Blinds, Deskscapes, Modern Mix, Start8, etc.
My guess is that even though Fences isn't using the desktop double-click, it's still intercepting it before the Directory Opus handler can. I've used DOpus since the 90's with version 4 on the Amiga - and literally use it all the time - usually from a double-click on the desktop. Hence, it's indespensible.
All the best,