I just ran into this on an older install. I had to reinstall to get past it.
<rant>To do that though, I needed to get to the Fusion Utility which was way more difficult than it needed to be because that stupid dialog just pops back up when you hit OK. The only way out is to find the executable in the Task List and kill it. (then relaunch with control-shift down, then reinstall)
It's wild that enough thought went into this process to create an article about the problem, but not enough to bother checking if you can quit the app.
