Is the problem when existing and restarting it? Or starting it at all? Or when it's already running?
What are you doing exactly, and what happens when you do that?
Is dopus.exe in Task Manager's Details tab? If it is and it's stuck in some way, please make some process snapshots and send them to us for analysis.
Which version causes the problem? Presumably one of the betas if going back to 13.18 makes it work again.