FWIW, the problem is definitely unrelated to the MSWord problem from 2008 that this thread was originally about.
From what I've looked at today, the issue is from the way Opus handles programs that register themselves in a particular way, which Winamp (and a handful of other programs) use, and a difference in how Opus handles the context menu vs pushing return to launch files.
There's a couple of ways we could fix it, and we're working out the best one at the moment.